Species Of Digenetic Trematodes Research Articles

5'-Nucleotidase activity and substrate affinity in digenetic trematodes.

5'-nucleotidases of eight species of digenetic trematodes were studied using five different substrates. All species showed the following preferential order of substrate affinity; AMP greater than CMP greater than GMP greater than TMP greater than UMP. It was observed that different species occupying similar habitats possessed closely related levels of enzyme activities. The function of 5'-nucleotidases in trematodes is also suggested.

Ultrastructure of Brachycoelium salamandrae Gastrodermis with Observations on the Effects of Starvation

The fine structure of the digestive tract of the digenetic trematode Brachycoelium salamandrae was studied. The digestive tract consisted of a foregut region whose lining was cytoarchitecturally similar to the general body tegument. Glands opened into the lumen of the foregut via microtubular-supported ducts. The junction between the foregut and the cellular gastrodermis was marked by a prominent desmosome. The apical plasma membranes of the gastrodermal cells were amplified by means of lamellae. The cells display an extensive rough endoplasmic reticulum, mitochondria, and numerous Golgi complexes. Two types of vesicles were observed. One type was a vesicle with a homogeneous matrix that appeared to be associated with the emitting face of Golgi complexes. Another structure was the multivesicular body that displayed acid phosphatase activity. This latter organelle was observed at times to be associated with autophagic vacuoles and is believed to be a part of the lysosome system of the gastrodermis. Starvation of the worms resulted in an increase in the disintegration of gastrodermal cells as well as an increase in the number of autophagic vacuoles in the cytoplasm. Ultrastructural organization of the adult diges- tive tract representative of nine families and 22 species of digenetic trematodes has been described to date (Fujino and Ishii, 1979). A number of cytochemical studies have supplemented the morphological studies and have provided invaluable information pertaining to the func- tion of portions of the digestive tracts of these organisms (see Erasmus, 1977, for a review). The objective of the present investigation was to study the ultrastructure of the digestive tract of Brachycoelium salamandrae, a trematode family whose ultrastructure has hitherto not been described. Preliminary cytochemical studies were made in order to compare distribution of acid phosphatase activity in both normal and starved worms. This aspect of the study was designed to provide greater understanding of the function of certain organelles associated with the digestive tract as well as provide a base for comparison of the distribution of the enzyme in B. salamandrae with that found in other digenea.

Recruitment of Digenetic Trematodes Using Caged Snails

Caged, laboratory-reared snails of two species (Physa gyrina and Lymnaea stagnalis appressa) recruited five species of digenetic trematodes in a natural stream habitat in Michigan from May through October, 1977. Temporal and spatial differences were observed in the infection rates of the two gastropod species. Many techniques have been devised to study the relationships between free-living stages of digenetic trematodes and their molluscan hosts. Successful measurement of the number of cercariae in field situations has been achieved (Rowan, 1957, 1965), but measurement of miracidial populations in nature has proven more difficult. Our study used caged, laboratory-reared snails to monitor the acquisition of trematode infections by snails in nature. This technique provides an indirect means to measure the low numbers of miracidia usually encountered in field situations. Application of this technique may provide information on seasonal periodicity of trematode infections and characterization of optimal sites of snail-miracidium interactions. Caged snails have been used by several workers to investigate miracidial dispersion of human schistosomes. McClelland (1965) designed small cylindrical cages made of perspex and mosquito netting to expose Bulinus nasutus snails to miracidia of Schistosoma haematobium. Webbe (1966) used caged Biomphalaria sudanica tanganyicensis to study the effects of water velocities on infection by S. mansoni, and Shiff (1968) investigated miracidial host-finding behavior over short distances using bulinid snails confined in small perspex cages. In a series of studies by Upatham (1972, 1973, 1976), caged B. glabrata were used to observe S. mansoni miracidial dispersion under laboratory and field conditions in St. Lucia. Upatham experimented with different cage designs and materials. Received 26 March 1981; revised 23 June 1981; accepted 5 October 1981. * Department of Zoology, Iowa State University, Ames, Iowa 50010. t Department of Biology, Hope College, Holland, Michigan 49423. An important difference between our study and all other work in this area is that in previous investigations miracidia were introduced into the habitat, usually in large numbers. No miracidia were artificially introduced in our study and therefore caged snails were exposed to numbers of miracidia present in natural habitats. MATERIALS AND METHODS This study was conducted from May through October, 1977 in a spring-fed stream running parallel to Highway U.S. 31 near Alanson in Emmet County, Michigan. The stream is located approximately 15 miles from the University of Michigan Biological Station and has been the focus of many studies involving digenetic trematodes. The stream is approximately 3 m wide and 21 cm deep and its bottom is covered by 0.5 m of mud. Water current in the stream was minimal, the average rate of flow having been measured at 0.02 m/second. Average daily water temperature varied from 10 to 11 C in May to 23 to 25 C in August. Cylindrical cages were placed at five sites, designated A through E, along a 304-m length of the stream. Dominant vegetation consisted of Chara, Nasturtium, Lemna, Potamogeton, and Typha. Stream fauna was characterized by large populations of aquatic gastropods, predominantly Lymnaea catascopium and Physa gyrina. Many other invertebrates, as well as several species of frogs, were observed in and around the stream. Redwinged blackbirds (Agelaius phoeniceus), common grackles (Quiscalus quiscula), and starlings (Sturnus vulgaris) used the trees near the stream as perching and nesting sites. Mammals frequenting the area included Microtus, Mus, Ondatra, Peromyscus, Rattus, and Zapus. An active muskrat den was located in the bank of the stream near Site D. Laboratory-reared P. gyrina and L. stagnalis were placed in cylinders constructed of 1.8-mm monofilament nylon mesh (Fig. 1). Cylinders measured 33 cm long by 12 cm in diameter and the open area of the mesh was approximately 60%. This allowed for uninterrupted flow of water. Seams were sewn with nylon thread and reinforced with a rubber-silicone aquarium sealer. Brass support frames were used to anchor cylinders in the stream bed. An alternate type of anchoring system was also

Seasonal Changes and Overwintering of Parasites in the Bat, Myotis lucifugus (Le Conte), in a Wisconsin Hibernaculum

During 1979-1980, eight digenetic trematode species, one cestode species and three nematode species were recovered from the little brown bat (Myotis lucifugus) at a southeastern Wisconsin hibernaculum. Statistically significant seasonal variation was observed for two digenetic trematodes. Mean densities and prevalence (%So of hosts infected) of parasites were highest in autumn and spring and lowest in summer. Highest species number occurred in autumn. Greater density and prevalence in autumn and spring may be correlated with bat swarming and emergence patterns, behavioral phenomena which would also produce a more heterogeneous assemblage of parasites during these times of the year. Myotis lucifugus retained high densities and prevalence of parasites throughout 8 months of hibernation.

Comparative ultrastructural topography of the gut epithelia of some trematodes

The gut epithelia of six species of digenetic trematodes, Clonorchis sinensis, Eurytrema pancreaticum, Haematoloechus lobatus, Echinostoma hortense, Schistosoma japonicum and Fasciola hepatica, were studied with scanning and also transmission electron microscopy. Morphological differences in cytoplasmic projections of the gut of adult flukes were demonstrated stereoscopically among these species. The cytoplasmic projections vary considerably in shape, but are roughly separated into three groups by their essential forms: ribbon-shaped narrow type in C. sinensis and E. pancreaticum, broad, triangular with filamentous extensions distally and/or marginally as in F. hepatica and E. hortense, and broad, sheet-like or triangular with the distal ends blunt or rounded as in H. lobatus and S. japonicum. This character appears rather constant, without regional differences in the gut. No marked correlation was found between the gut projections of the parasites and their host or food. There are also specific discriminations in the ultrastructure of the cellular organization among the species examined.

Three species of Digenea from the Atlantic leatherback turtle (Dermochelys coriacea).

Three species of digenetic trematodes (Pyelosomum renicapite, Calycodes anthos, Cymatocarpus sp. (?)), are reported from two Atlantic leatherback turtles (Dermochelys coriacea) taken off the coast of Newfoundland and Labrador, in 1973. The status of the genera Pyelosomum Looss, 1899 and Astrorchis Poche, 1925 is discussed.

Allometric Growth in Four Species of Digenetic Trematodes of Marine Fishes from Belize

Four species of digenetic trematodes of marine fishes from Belize are studied for allometric growth: Multitestis rotundus Sparks, 1954 (Lepocreadiidae), Stenopera equilata Manter, 1933 (Opecoelidae), Leurodera decora Linton, 1910 (Hemiuridae), Prosorhynchus pacificus Manter, 1940 (Bucephalidae). These are compared with six other species for which allometric growth is known. Positive growth is exhibited in all species only by the hindbody, whereas the forebody, suckers, and pharynx are negative in all. The body width, post‐testicular body, and gonads are positive in some species and negative in others. At times the body proportion or organ is growing at about the same rate as the body length.

New marine hosts for Parorchis acanthus, Cryptocotyle lingua, Maritrema megametrios, and Maritrema gratiosum, trematodes of birds from British Columbia, Canada

New molluscan, crustacean, and avian hosts were found for four species of digenetic trematodes in Vancouver, British Columbia, from 1973 to 1977. The rediae and cercariae of Parorchis acanthus (Nicoll) were discovered in Nucella lamellosa (Gmelin). Adults were recovered after 19 days from experimental feedings of the metacercariae to a newly hatched domestic chick. The cercariae of Cryptocotyle lingua (Creplin) from the snail Littorina scutulata Gould were used to infect young fish, Leptocottus armatus Girard, Oligocottus maculosus Girard, and Platichthys stellatus (Pallas). These fish, infected with the metacercariae, were fed to newly hatched gulls, Larus glaucescens Naumann, and mature worms were found in the anterior half of the intestine after 14 and 21 days. The metacercariae of Maritrema megametrios Deblock and Rausch, found in Orchestia traskiana Stimpson and Gnorimosphaeroma oregonense (Dana), became ovigerous in Locke's solution at 40 °C at 48 h. Natural infections were found in Larus Philadelphia (Ord). The metacercariae of Maritrema gratiosum Nicoll, found in Balanus glandula Darwin, also became ovigerous in vitro. Adults were found with two other microphallid species in the intestine of one Bucephala islandica (Gmelin).

Allometric growth in three species of digenetic trematodes of marine fishes from Belize.

Allometric growth of body proportions and organs is determined for three speciies of digenetic trematodes of marine fishes from Belize: Apocreadium mexicanum Manter, 1937 (Apocreadiidae), Pseudocreadium lamelliforme (Linton. 1907) Manter, 1946 (Lepocreadiidae), Paracryptogonimus americanus Manter, 1940 (Cryptogonimidae). These are compared with three other species in which allometric growth has been studied. In all species only the hindbody shows positive growth, whereas the forebody, suckers, and pharynx are consistently negative. The body width, posttesticular body, testes, and ovary are positive in some species and negative in others. In some instances the body proportion or organ is growing at the same rate as the body length.

Observations on the structure and histology of the gut in some digenetic trematodes

In a study on 20 species of digenetic trematodes belonging to 13 families we could recognise six basic histological conditions (1). Gastrodermis of uniform height without any brush border (2). Gastrodermis of uniform height but with microvilli (3). Gastrodermis which presents pyramidal ridges projecting into the lumen in the absence of food but more or less of uniform height in the presence of food. In both the stages characteristic microvilli make their appearance (4). Gastrodermis presents two different stages—when the lumen is free of food the cells are club-shaped or columnar or cylindrical and when food is present it shrinks to flat or cuboidal gastrodermis (5). Two stages of gastrodermis as mentioned in the previous condition but the brush border makes its appearance only in the flat cell condition (6). Two stages of gastrodermis—in both the stages the brush border is present. Thus six different gastrodermal organisations could be made out. The histological structure seems to be independant from the family to which the parasite belongs or its habitat or food habits.

Quantitative studies on acetylcholinesterase in seven species of digenetic trematodes.

Quantitative estimation of absolute levels and in vitro release of acetylcholinesterase (AChE) in seven species of digenetic trematodes: Isoparorchis hypselobagri from the swim bladder of catfish, Wallago attu; Srivastavaia indica and Gastrothylax crumenifer from the rumen, and Gigantocotyle explanatum from the liver of the water buffalo, Bubalus bubalis; Fasciolopsis buski, Echinostoma malayanum from the small intestine and Gastrodiscoides hominis from the caecum of the pig, Sus scrofa revealed that the enzyme is present in remarkably high quantities in species which inhibit gastrointestinal tract compared with those that parasitize liver and swim bladder. The rate of in vitro release of AChE also varies with the species which supports the view that such differential secretion probably takes place in situ as well to counteract peristalsis and it is a biochemical adaptation on the part of these trematodes.

Two New Species of Digenetic Trematodes of Fishes From the Bay of Bengal

Diagnoses are given of the digenetic trematodes Neohysterolecitha indica n.gen., n.sp. and Opisthomonorcheides indicus n.sp. They were collected from the stomach of the fish Chirocentrus dorab (Ruppel) and the intestine of the fish Apogonichthys ellioti (Day), respectively, both from the Bay of Bengal, off the Puri coast, Orissa, India.

A brachylaimid trematode from marsupial mice with observations on its life cycle

A species of digenetic trematode, Brachylaime antechini (Family Brachylaimidae), is described from adult worms recovered from the intestine and rectum of two species of marsupial mice, Antechinus stuartii(10 of 56 infected) and Antechinus swainsonii (2 of 5 infected). On experimental evidence unencysted metacercariae from the kidney of a terrestrial gastropod, Strangesta capillacea, are considered to be larval stages of Brachylaime antechini. Miracidia, sporocysts and cercariae have not been recovered, but circumstantial evidence suggests that Strangesta capillacea fulfils the role of first intermediate host. Brachylaime antechini most closely resembles Brachylaime chiapensis, a parasite of deer mice in Mexico.

Observations on Ligated Adults of Philophthalmus megalurus, Gorgoderina attenuata, and Megalodiscus temperatus by Scanning Electron Microscopy and Autoradiography

Scanning electron micrographs showed damage to the tegument adjacent to ligatures of adult Philophthalmus megalurus, Gorgoderina attenuata, and Megalodiscus temperatus. Leakage of tritiated tyrosine, leucine, and thymidine was detected around the ligatures on adult P. megalurus by an autoradiographic method that localizes soluble compounds. Grain counts were significantly higher adjacent to ligatures than elsewhere. Autoradiography did not indicate leakage in some ligated worms, but all observed with the scanning electron microscope exhibited tissue damage. The technique of ligation is thus considered unreliable for absorption studies involving digenetic trematodes. Investigations studying the uptake and incorporation of metabolites by various digenetic trematodes have utilized ligation to close off the gut from the external environment (Mansour, 1959; Kuralec and Erhlich, 1963; Isseroff and Read, 1969; Isseroff and Walczak, 1971; Pappas, 1971; Nollen et al., 1973; Nollen et al., 1974). In a monogenean, Diclidophora merlangi, Halton and Arme (1971) found such ligation to increase significantly the uptake of a labeled compound as determined by a counting technique. They also observed by transmission electron microscopy (TEM) damage to tissue near ligatures, used Evan's blue to detect such injury in living worms, and stressed the importance of intact specimens for investigating the uptake of metabolites through the tegument. Their findings suggested this study which deals with three species of digenetic trematodes previously used for ligation experiments, and utilized scanning electron microscopy (SEM) and autoradiography to detect tissue leakage near ligatures and its effect on uptake of labeled amino acids and thymidine. MATERIALS AND METHODS Adult Philophthalmus megalurus were obtained from the conjunctival sac of chicks infected for 25 to 32 days. Gorgoderina attenuata and Megalodiscus temperatus were removed from the bladder and rectum of Rana pipiens from commercial sources. For SEM worms were ligated just beReceived for publication 21 February 1974. hind the oral sucker with 6-0 surgical silk and fixed in phosphate-buffered 5% glutaraldehyde (pH 7.3) for 30 min, rinsed in the buffer, and postfixed in phosphate-buffered 1% osmium tetroxide (pH 7.3) for 30 min. They were dehydrated through a graded series of ethyl alcohol, mounted on stubs using conductive silver paint, coated with gold, and examined in a Cambridge Stereoscan SEM Model II-A. For autoradiography, 5 ligated P. megalurus adults were exposed to each of 3 tritiated compounds (Amersham/Searle) (L-tyrosine 3,5-T, sp. act. 1 Ci/mmole; L-leucineT-G, sp. act. 200 mCi/mmole; and thymidine methyl-T, sp. act. 3.0 Ci/mmole) diluted in 2 ml of Hedon Fleig's saline and processed for localization of water-soluble compounds by the method of Wilske and Ross (1965) as modified by Nollen (1968). Grain counts were made with a Whipple eyepiece micrometer grid at 1,500x. For each worm at least 25 areas 100 u' were counted for tissues adjacent to the ligature and the tegument posterior to the ligature. Student's t test was used to determine the significance of differences in mean grain counts.

Viability of a Self-Fertilizing Strain of Philophthalmus megalurus (Trematoda: Digenea)

A self-fertilizing strain of Philophthalmus megalurus was carried through 3 successive life cycles with little or no deleterious effects when compared with cross-fertilizing strains. No significant differences in the parameters of growth, eggshell formation, and the production of viable miracidia and cercaria were noted. However, significant reductions in recovery rates of adults from monometacercarial infections in the 2nd and 3rd generations were found. The effects of self-fertilization on different species of digenetic trematodes and cestodes and possible evolutionary adaptations for survival of self-fertilizing strains are discussed. The question of whether the hermaphroditic digenetic trematodes reproduce by selfor cross-fertilization has interested parasitologists for many years. Stunkard (1957) asserted that parasitic flatworms do not occur in interbreeding populations and reproduce by self-fertilization. Smyth (1962) suggested that self-fertilization is the most common type of reproductive process in the digenetic trematodes. On the other hand, Martin (1969) stressed the importance of intraspecific cross-fertilization for interpreting the biological species concept based on data from a study with Philophthalmus megalurus by Nollen (1968) and other studies utilizing different species of digenetic trematodes. The importance of cross-fertilization for development of the life cycle is another question to be answered now that it is known cross-insemination takes place in some species of digenetic trematodes. In the genus Philophthalmus the situation seems to vary among different species. Nollen (1971a) found that isolated adults of P. megalurus grow as well as those in multiple infections, and he was able to carry this eye fluke through one complete life cycle with no evidence of deterioration. On the other hand, Fried (1962) found that isolated adults of P. hegeneri stopped growing after 20 days in a chick's eye and never produced fertile eggs. Working with a similar Received for publication 20 May 1971. * This investigation was supported by the United States-Japan Cooperative Medical Sciences Program administered by the NIAID; Grant AI 09330. fluke, Howell and Bearup (1967) noted that single-worm infections of Philophthalmus burrili were infertile and contained no recognizable seminal receptacle. A similar situation in which species of a genus differ as to the viability of isolated adults also seems to occur in the genus Paragonimus. Sogandares-Bemal (1966) found that monometacercarial infections of cats with Paragonimus kellicotti never developed beyond the wandering preadult stage. However, Fan and Chiang (1970) found single infections of Paragonimus westermani in kittens and puppies developed into mature adults producing eggs capable of hatching. Varied results have been obtained with isolated adults of other digenetic trematodes. Bacha (1966) found that eggs produced by a second generation of isolated adults of Zygocotyle lunata in rats hatched less readily than those from multiple infections. Sogandares-Bernal (1965) found a higher percentage of paired adults of Microphallus opacus, which were excysted and maintained in vitro, produced eggs than those maintained in isolation. Viability of these eggs was not determined. Beaver (1937) and Lie (1965) observed normal miracidial development and hatching in single infections with species of Echinostoma. In this study successive life cycles of P. megalurus were investigated because this species grows and develops normally in isolated situations, and has proved viable for at least one self-fertilizing generation. A major drawback was the difficulty of raising the snail intermediate host, Pleurocera acuta. This was partially

Digenetic trematodes: Quinone tanning system in eggshells

Three species of digenetic trematodes with colorless and transparent eggshells, Philophthalmus megalurus, Gorgoderina attenuata, and Megalodiscus temperatus, were compared by histochemical tests with Haematoloechus medioplexus, which has an identifiable quinone tanning system. Precursors for tanning including basic and tyrosine-rich proteins were identified histochemically in all species. Autoradiograms indicated that tyrosine was taken up after in vitro exposure of adult worms by vitelline tissue of G. attenuata and M. temperatus, but at a slower rate in the latter species. Protein synthesis inhibitor studies utilizing cycloheximide showed a reduction of tyrosine incorporation in the vitelline tissue of G. attenuata suggesting that tyrosine is incorporated into protein. Inhibition in M. temperatus was negligible, but evidence from other studies indicated absorption of cycloheximide by the adult may be minimal. Phenolase could not be found in G. attenuata and M. temperatus but was identified in P. megalurus. However, the enzyme system in the latter species seemed to be a partial one capable of oxidizing dihydroxyphenols but not monohydroxyphenols. Histochemical and solubility tests for keratin-type protein in the eggshells were inconclusive. It is suggested that positive identification of keratin as a structural protein of trematode eggshells be withheld until more reliable techniques can be employed. Possible evolutionary implications of the tanned eggshell in the Digenea are discussed.

Parasites of the flounder - Platichthys flesus (L.) from the brackish water of Kamieński Bay

A number of 116 specimens of Platichthys flesus (L.), of the total body length 14.5-28.5 cm, was examined for parasites. The fishes were caught during the spring of 1968 in Szczecin Lagoon in the vicinity of Kamień Pomorski. Thirteen species of parasites were found, including 4 species of digenetic trematodes, 1 species of cestode, 3 species of nematodes and 5 species of acanthocephalans. A total number of 75 fishes, i.e., 65.64%, was infested. There were found 4 species of parasites of marine origin.

Ingestion in Two Species of Digenetic Trematodes

Ingestion in Two Species of Digenetic Trematodes

Digenetic trematodes from Newfoundland, Canada. 1. Three species from Gasterosteus aculeatus Linnaeus, 1758

Three species of digenetic trematodes are recorded from the three-spined stickleback, Gasterosteus aculeatus Linnaeus, 1758, namely Podocotyle atomon (Rudolphi, 1802), Brachyphallus crenatus (Rudolphi, 1802), and Lecithaster gibbosus (Rudolphi, 1802). The latter two species are new host records for North America.

The Trematode Parasites of the Sheathbill, Chionis alba (Gmelin), from Signy Island, South Orkney Islands

This paper reports on two species of digenetic trematodes, namely Gymnophallus deliciosus (Olsson, 1893) and Notocotylus chionis Baylis, 1928, from Sheathbills collected on Signy Island.(lat. 60° 43' S., long. 45° 36' W.), South Orkney Islands, in July and October 1965 by Mr Charles Howie of the British Antarctic Survey. The birds were preserved in deep-freeze and later passed to us for examination. An account of the cestode parasites of these birds has been given previously (Jones & Williams, 1967).