Das Miracidium von Isthmiophora melis (Schrank, 1788) (Echinostomatidae)

Zusammenfassung Die Entwicklung des Miracidiums von Isthmiophora melis dauert bei 22° C mindestens 14 Tage und durchschnittlich 18 Tage, bei 29° C mindestens 8 Tage und durchschnittlich 9 Tage. Miracidien mit endogen bedingter Entwicklungsverzögerung wurden bei I. melis nicht beobachtet.Bei Temperaturen unter 15° C können vollentwickelte Miracidien bis 90 Tage lang lebend und schlüpfbereit in der Eikapsel überdauern. Das Schlüpfen wird durch Temperaturerhöhung auf 26° C ausgelöst. Gleichzeitige Beleuchtung verstärkt die Wirkung einer Temperaturerhöhung. Beleuchtung allein ist aber von geringerer Wirkung als Temperaturerhöhung allein. Spontanes Schlüpfen einzelner Miracidien wurde nur bei Temperaturen von 22° C beobachtet.Die Dauer der Schwimmaktivität des geschlüpften Miracidiums beträgt bei 22° C bis zu 11 Std. Das Verhalten der Miracidien wird durch starke positive Phototaxis beherrscht. Geotaxis konnte nicht nachgewiesen werden, weder im Hellen noch im Dunkeln.Die Epithelzellformel des Miracidiums lautet 6+9+4+2=21. Hierin weicht I. melis von den meisten anderen Echinostomatiden ab, deren Miracidien im zweiten Epithelzellring nur 6 Zellen besitzen. Eine 4-kernige Apicaldrüse, 1 Paar pigmentierte Ocellen, 2 Lateralpapillen, 6 Radiärpapillen und 2 Protonephridien sind vorhanden.Die Epithelzellformeln aller Echinostomatiden-Miracidien, soweit beschrieben, sind in der Tabelle 1 kollationiert.

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The miracidium of Isthmiophora melis (schrank, 1788) (echinostomatidae)Ecology and morphological features

Summary The development of the miracidium of Isthmiophora melis requires at a temperature of 22° C a minimum period of 14 days, and a mean period of 18 days; at 29° C a minimum period of 8 days, and a mean period of 9 days. Retarded development and prolonged hatching, caused by endogenic factors, has not been observed in the miracidia of I. melis.At temperatures below 15° C the developed miracidium inside the egg capsule can stay alive and ready for hatching for a period up to 90 days. Hatching is caused by an increase in temperature to 26° C. The effect of an increase in temperature is enhanced by simultaneous exposure to light. But exposure to light alone is less effective than an increase in temperature. Spontaneous hatching was observed only at temperatures of 22° C.The hatched miracidium will swim for 11 hours if the temperature is maintained at 22° C. In the behavior of the miracidium the most prominent feature is a strong positive phototaxis. Geotaxis was not established, neither in the light nor in the dark.The epithelial cells of the miracidium are arranged in four circles of 6, 9, 4, and 2 cells. In this pattern I. melis differs from most other echinostomatids which have 6 cells in the second circle. Other features of the miracidium of I. melis are an apical gland with 4 nuclei, a pair of pigmented ocelli, 2 lateral papillae, 6 radiar papillae, and 1 pair of flame cells.The epithelial cell patterns of all echinostomatid miracidia, which have so far been described, are collated in a table.

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Dem ehrenden Andenken an Prof. Dr. med. Ludolph Fischer (27. 4. 1900–29. 12. 1972) gewidmet.

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Die Untersuchung wurde mit Unterstützung durch die Deutsche Forschungsgemeinschaft ausgeführt.     

Studies on the attachment response ofIsthmiophora melis cercariae (Trematoda: Echinostomatidae)

The cercaria ofIsthmiophora melis is relatively specific to suitable intermediate hosts, amphibia and fish, as early as the stage of attachment. Attachment responses are maximally stimulated by intact amphibia, whereas isolated frog tissues have a reduced efficiency. Human urine contains attachment triggering substances. Its effectiveness is reduced, when carbonate systems are removed, and may be restored by addition of carbonate. Aqueous solution systems of dissolved CO₂ and H₂CO₃/HCO ₃ ^– stimulate attachment responses, especially at pH 6.0–7.5. The attachment response to frog skin surface seems to be triggered by the buffering system, which uses carbonate solution equilibria as important components.     

Der modifizierende Einfluß des Endwirtes auf die Entwicklung des Darmegels Isthmiophora melis (Schrank, 1788)

Zusammenfassung Zwei Wanderratten (Rattus norvegicus) wurden experimentell mit dem Darmegel Isthmiophora melis infiziert. 29% der verabfolgten Metacercarien entwickelten sich zu Adulten oder Adolescarien, während bei früheren Versuchen mit weißen Ratten die Ansitz-Quote nur 10% betrug. Die gewonnenen Würmer entsprechen der Entwicklungsmodifikation von Isthmiophora aus der weißen Ratte. Die Synonymität von Echinostoma spiculator Dujardin (1845) mit Isthmiophora melis Schrank (1788) ist dadurch verifiziert.In einer Wanderratte des Federsee-Gebietes wurde eine natÜrliche Infestation mit Isthmiophora melis festgestellt.

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The modifying effect of the final host on the development of the intestinal fluke Isthmiophora melis (schrank, 1788)III. The development in the brown rat (Rattus norvegicus), a natural final host

Summary Two Brown Rats (Rattus norvegicus) were experimentally infected with the Intestinal Fluke, Isthmiophora melis. 29% of the metacercariae fed to them developed into the adult or pre-adult stage. In former experiments with white laboratory rats not more than 10% of the metacercariae developed into the adult or pre-adult stage. The flukes from the Brown Rats correspond with the modification from the white rat. Thus, the synonymity of Echinostoma spiculator Dujardin (1845) with Isthmiophora melis Schrank (1788) is confirmed.A wild Brown Rat from a South German lake was found naturally infested with Isthmiophora melis.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Der modifizierende Einfluß des Endwirtes auf die Entwicklung des Darmegels Isthmiophora melis (Schrank, 1788)

Zusammenfassung Zwei Läuferschweine wurden mit Metacercarien des Darmegels Isthmiophora melis (Schrank, 1788) infestiert. Die gewonnenen Adultwürmer entsprechen der Form Euparyphium suinum Ciurea 1921, die demnach artgleich mit Isthmiophora melis ist. Entwicklungsgeschwindigkeit und generative Aktivität des Parasiten sind im Schwein (Sus scrofa) geringer als in der weißen Ratte (Mus norvegicus) und viel geringer als im Frettchen (Putorius furo). Merkmalsunterschiede der drei Entwicklungsmodifikationen von I. melis aus Schwein, weißer Ratte und Frettchen sind nur auf quantitativ-statistischem Wege eindeutig faßbar.

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The Modifying effect of the final host on the development of the intestinal fluke Isthmiophora melis (Schrank, 1788)II. Euparyphium suinum Ciurea, 1921, a synonym of Isthmiophora melis

Summary Two young pigs were experimentally infested with Metacercariae of the intestinal fluke, Isthmiophora melis (Schrank, 1788). The adult flukes which resulted correspond with Euparyphium suinum Ciurea 1921; thus the latter is synonymous with Isthmiophora melis. Rate of development and generative activity of the parasite are smaller in the pig than in the laboratory rat and much smaller than in the ferret. Morphologic differences existing between the three modifications of I. melis from pig, laboratory rat, and ferret can be recorded only statistically.

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Herrn Prof. Dr. Curt E. W. Sprehn zum 75. Geburtstage in Verehrung gewidmet.     

The life-history ofMesorchis denticulatus (Rudolphi, 1802) Dietz, 1909 (Trematoda,Echinostomatidae)

Red-tailed gigantocercous cercariae which developed in the euryhaline snailHydrobia ulvae Pennant (Prosobranchia, Hydrobiidae) in Denmark developed intoMesorchis denticulatus (Rudolphi 1802) Dietz 1909 (Echinostomatidae). Synonyms areStephanoprora denticulata (Rudolphi 1802) Odhner 1910,M. pseudoechinatus (Olsson 1876) Dietz 1909, andS. pseudoechinata (Olsson 1876) Odhner 1910. The rediae are cannibals devouring whole extraredial cercariae. The cercariae are actively ingested by small fish or carried by the respiratory current into their gill chambers. They encyst in the gill filaments.Gasterosteus aculeatus L.,Pungitius pungitius L. andPomatoschistus microps Krøyer are the most important second intermediate hosts in Danish waters, but all species of small fish, exceptAnguilla anguilla L., exposed to the cercariae were experimentally infected. Chickens were suitable laboratory hosts, whereasLarus spp. and other piscivorous birds function as natural final hosts in Europe and North America. Mammals may also be suitable hosts.     

Tegumentary papillae of Echinostoma caproni cercariae (Trematoda: Echinostomatidae)

Argentophilic staining and scanning electron microscopy were used to study the tegumentary papillae of Echinostoma caproni cercariae. The most abundant tegumentary papillae were uniciliate, but multiciliate papillae were also found, mainly on the ventral aspect of the oral collar. The distribution pattern of the papillae on the body and tail was in general similar to that seen in the cercariae of other 37-collar-spined Echinostoma species. Some differences were noted between E. caproni and the allopatric species, E. trivolvis. E. caproni has a greater number of papillae associated with the collar spines than does E. trivolvis. E. caproni has uniciliate papillae on the acetabulum, whereas E. trivolvis does not. Chaetotaxy is useful to distinguish subtle morphological differences in cercarial species in the 37-collar-spined Echinostoma complex.     

Der modifizierende Einfluß des Endwirtes auf die Entwicklung des Darmegels Isthmiophora melis (Schrank 1788)

Zusammenfassung Der Darmegel Isthmiophora melis (Schrank, 1788) entwickelt sich in der weißen Ratte (Rattus norvegicus) zu einer signifikant kleineren Modifikation als im Frettchen (Putorius furo). Beide Modifikationen unterscheiden sich nicht nur in den absoluten Massen, sondern auch in den Größenrelationen der Organe. Die Gesamtlänge des Wurmes als Vergleichswert zugrunde gelegt, sind bei den in Ratten gezogenen Adultwürmern die generativen Organe (Ovar ausgenommen) geringfügig schwächer, alle vegetativen Organe dagegen wesentlich stärker entwickelt als bei den aus Frettchen erhaltenen Adulten. Dennoch ist die Ratte ein vollwertiger Endwirt, in dem der Parasit die Reife erlangt. Isthmiophora-Eier aus Ratten sind im Mittelwert um 3% kleiner als solche aus Frettchen. Die Präpatentperiode ist bei Ratten durchschnittlich um 3 Tage länger als bei Frettchen, die Gesamtdauer der Infestation bei Frettchen länger als bei Ratten.Die Entwicklungsmodifikation des Wurms aus der Ratte entspricht der Form Echinostoma spiculator Dujardin (1845), die aus dem Frettchen der Form Isthmiophora melis (Schrank, 1788). Ersterer Name ist folglich ein Synonym des letzteren.Es wird bewiesen, daß die Gattung Isthmiophora Lühe 1909 sich nicht mit der Gattung Euparyphium Dietz 1909 deckt. Die von Odhner 1911 disqualifizierte Gattung Isthmiophora besteht zu Recht.

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The modifying effect of the final host on the development of the intestinal fluke Isthmiophora melis (Schrank, 1788)A rehabilitation of genus Isthmiophora Lühe, 1909 (Trematoda, Echinostomatidae)

Summary In the laboratory rat (Rattus norvegicus), the intestinal fluke Isthmiophora melis (Schrank, 1788) develops into a significantly smaller modification than in the ferret (Putorius furo). The two modifications differ not only in their absolute measurements but also in the relative size of their organs. Compared with the total length, adult worms grown in rats have considerably larger vegetative organs and somewhat smaller generative organs (with the exception of the ovary) than those from ferrets. Nevertheless, the rat is a suitable final host in which the parasite reaches maturity.On the average, Isthmiophora eggs from rats are smaller by 3% than those from ferrets, the prepatent period is 3 days longer in rats, and the duration of infestation is longer in ferrets.The modification of the worm found in rats corresponds with Echinostoma spiculator Dujardin 1845, the one developing in ferrets with Isthmiophora melis (Schrank, 1788); thus the former is synonymous with the latter.The genus Isthmiophora Lühe 1909 is not identical with the genus Euparyphium Dietz 1909, i.e. Isthmiophora, which was disqualified by Odhner in 1911, must be considered a true genus.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Ultrastructure of the Miracidium of Echinostoma paraensei Lie and Basch, 1967 (Trematoda, Echinostomatidae)

The morphology of Echinostoma paraensei was studied using transmission electron microscopy. The terebratorium region has many electrondense secretory granules and many folds on the surface. The epidermal cells that cover the larval body have unique nuclear morphology, many mitochondria and vesicles being attached to the interepidermal ridges by a septate junction. The cilia present the organization 9+2 and a typical structure with a shaft, axosome, basal body and rootlet. Below the epidermal cells there is a layer of circular muscle and, adjacent to it, a layer of longitudinal muscle fibers. The excretory system has two flame cells, with internal and external ribs and leptotriches at the barrel region, an excretory vesicle and an excretory pore.     

Impairment of long-term associative memory in aging snails (Lymnaea stagnalis)

Age-dependent impairment in learning and memory functions occurs in many animal species, including humans. Although cell death contributes to age-related cognitive impairment in pathological forms of aging, learning and memory deficiencies develop with age even without substantial cell death. The molecular and cellular basis of this biological aging process is not well understood but seems to involve a decline in the aging brain's capacity for experience-dependent plasticity. To aid in resolving this issue, we used a simple snail appetitive classical conditioning paradigm in which the underlying molecular, cellular, and neural network functions can be directly linked to age-associated learning and memory performance (i.e., the Lymnaea stagnalis feeding system). Our results indicate that age does not affect the acquisition of appetitive memory but that retention and/or consolidation of long-term memory become progressively impaired with advancing age. The latter phenomenon correlates with declining electrophysiological excitability in key neurons controlling the feeding behavior. Together, these results present the Lymnaea feeding system as a powerful paradigm for investigations of cellular and molecular foundations of biological aging in the brain.     

Cercarial chaetotaxy of Echinostoma revolutum (Froelich, 1802) and E. echinatum (Zeder, 1803) (Trematoda, Echinostomatidae)

The life-cycles of Echinostoma revolutum and E. echinatum were carried out by using cercariae emitted by naturally infected Molluscs. E. revolutum strain was issued from Lymnaea auricularia, E. echinatum from Lymnaea truncatula and Planorbis planorbis, Planorbarius corneus produced an Echinostome which may possibly be E. echinatum or another species E. sp. Metacercarial stages and adults were obtained from laboratory experimental hosts. None of these adult Echinostomes displayed well-defined morphological differences: nevertheless their respective larval stages exhibited discrepancies used for species diagnosis. Cercarial chaetotaxy is given for every batch and compared with that of other species described as E. audyi, E. lindoense and E. caproni; discriminating features are discussed.     

Identification and distribution ofEchinostoma lindoense,E. audyi andE. revolutum (Trematoda; Echinostomatidae)

The closely relatedEchinostoma lindoense, E. audyi andE. revolutum can be differentiated by morphological characteristics of their adults and cercariae. We have foundE. lindoense andE. audyi in Southeast and Southwest Asia and Central Europe and the former species also in South America. However, using the morphological characteristics described by Beaver (1937) forE. revolutum which is assumed to be cosmopolitan, we did not find this species in these regions.     

Experimentelle Untersuchungen über Bau,Entwicklung und Systematik der Himasthlinae (Trematoda,Echinostomatidae) des Nordseeraumes

Ohne ZusammenfassungMit Unterstützung der Deutschen Forschungsgemeinschaft und Forschungsmitteln des Landes Niedersachsen.     

Scanning electron microscopy of rediae,cercariae, metacercariae and adults of Mesorchis denticulatus (Rudolphi, 1802) (Trematoda,Echinostomatidae)

A detailed study of the surface topography of the echinostome digenean Mesorchis denticulatus (Rudolphi 1802) Dietz 1909 was carried out using the scanning electron microscope. The surface area of the redia is increased by microvilli, and ciliate sensory structures are common around the mouth. The cannibalistic behaviour of the rediae is demonstrated by rediae which have the posterior end and tail of extraredial cercariae protruding from the mouth. The partly devoured cercariae had occasionally — apparently as a defence reaction — covered their bodies with a thick layer of cystogenous material, which, however, does not protect them from being eaten.The surface area of the tegument of the youngest extraredial cercariae is increased by small microvilli or knobs with a presumed function in nutrient absorption. The knobs disappear when the cercariae are fully developed. Flattened spines occur peripherally in the suckers. Different types of ciliate structures are especially common anteriorly. The infective metacercariae, which occur in the gill filaments of euryhaline fishes, have conspicuous collar spines and smaller pointed spines occur on most of the body surface.The spines continue to grow in the experimental final host, chickens. The flattened spines of the oral sucker remain, whereas those of the ventral sucker disappear. The ventral area between the suckers is spineless.     

A new Ig-superfamily member,molluscan defence molecule (MDM) from Lymnaea stagnalis,is down-regulated during parasitosis

To survive the attacks of the internal defence system (IDS) of their host, parasites have developed various strategies to manipulate the IDS. We present evidence that the avian schistosome parasite Trichobilharzia ocellata affects gene expression in the granular cells, a cell type of the IDS of the intermediate host, the mollusc Lymnaea stagnalis. From a differential screening, a clone was isolated encoding a protein named molluscan defence molecule (MDM), which encompasses five C2-like immunoglobulin (Ig) domains. The protein shares a domain organization and high amino acid sequence identity with hemolin, an Ig-family member of the insect IDS. Interestingly, both MDM and hemolin have highest sequence identity with neural cell adhesion molecules, but lack the typical fibronectin repeats and motifs for membrane anchors. We find that the expression of the MDM gene is gradually down-regulated during the course of parasitosis to ～21% compared to the non-parasitized level, 8 weeks post-infection. Based on our findings, we suggest that MDM is involved in the proper functioning of the Lymnaea IDS, and that down-regulation of MDM is part of the parasite-induced disabling of non-self recognition.     

Comparative ultrastructure of eggs in Echinostoma paraensei, E. caproni, and E. trivolvis (Trematoda: Echinostomatidae)

The 37-collar-spined echinostomes Echinostoma paraensei, E. caproni, and E. trivolvis are digeneans that live in the intestine of small mammals and birds. Comparative studies of the eggs of these species were done using light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The egg of E. caproni was the largest of the three species studied, whereas the egg of E. trivolvis was the smallest in both length and width. The SEM study showed differences in the aboperculum region of the eggs in all three species. The TEM study showed that the eggshell of all three species consisted of three layers, but no difference in eggshell structure was observed in any species. Received: 10 September 1999 / Accepted: 9 November 1999     

Biochemical profile of Biomphalaria glabrata (Mollusca: Gastropoda) after infection by Echinostoma paraensei (Trematoda: Echinostomatidae)

The effect of infection by Echinostoma paraensei on the activity of the enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and the concentration of total proteins, uric acid and urea in the hemolymph of Biomphalaria glabrata were investigated after exposure to five or 50 miracidia. The biochemical concentrations were measured weekly until the end of the fourth week after exposure. There was a significant decrease in the concentrations of total proteins in the snails exposed both to five and 50 miracidia, as well as an increase in the nitrogenous products of excretion, ALT and AST activities. The higher ALT activity in the hemolymph of the snails after infection with 50 miracidia suggests highest energetic requirement in these snails in relation to snails exposed to five miracidia. The results also suggest an increase in the use of total proteins, since there was increased formation of nitrogenous catabolites, in conformity with an increase in the aminotransferase activities, frequently associated with tissue damages. This can be explained by damage due to penetration by the miracidia and subsequent development of intramolluscan sporocysts and rediae.     

Curtuteria numenii nov. gen., nov. sp. aus Numenius Phaeopus (L.) (Trematoda,Echinostomatidae, Himasthlinae)

Zusammenfassung Es wird der Vertreter einer neuen Gattung beschrieben, Curtuteria numenii gen. nov., spec. nov., Trematoda, Echinostomatidae, Himasthlinae, aus dem Dünndarm von Numenius phaeopus (L.) von der Insel Hiddensee in der mittleren Ostsee. Von der Gattung Himasthla trennt ihn die Kürze des Uterus, ein deutlich abgegrenzter kleiner Prostatabezirk und die zahlreichen Divertikel der Exkretionshauptstämme im Vorderkörper, von Acanthoparyphium die Zahl der Kopfkragenstacheln (nicht 23, sondern 29) und das Fehlen eines hinteren Körperabschnitts hinter den Hoden, der bei Acanthoparyphium von den Dotterstöcken erfüllt wird.Mit 2 Textabbildungen