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At least 127 records · Page 7Linked to original sources
PubMed1995

The central nervous system of Grillotia erinaceus (Cestoda: Trypanorhyncha) as revealed by immunocytochemistry and neural tracing.

Immunofluorescent labeling and neural tracing techniques were employed in conjunction with confocal scanning laser microscopy to study the intact neuroanatomy of the central nervous system of the trypanorhynch tapeworm Grillotia erinaceus. Immunocytochemical labeling for the general nerve fibre marker PGP 9.5 showed a pattern of extensive labeling that paralleled findings obtained with the neural tracer DiI. In contrast, immunocytochemical labeling for 5-hydroxytryptamine (5-HT) was localised to cell bodies lying on the periphery of the ganglion, with fine immunoreactive fibres radiating out towards the bothridia. Following the retrograde transport of the fluorescent molecule DiI through axotomised nerve cords, it successfully labeled both the cerebral ganglion and associated nerve fibres within the scolex. The cerebral ganglion was shown to give rise to posterior nerve cords, an array of radial fibres that pass out to the bothridia, and to contain a centrally disposed group of cell bodies thought to be involved in efferent functions.

Animals↗
PubMed1992

A double surface membrane in plerocercoids of Ligula intestinalis (Cestoda: Pseudophyllidea).

The tegument of Ligula intestinalis plerocercoids is delimited by a membrane complex that in electron microscopy appears heptalaminate. We suggest that the plerocercoids are covered by two closely apposed lipid bilayers. Double membranes, which are well known in schistosomes, are thus not a unique feature of blood parasitic Digenea but could be documented for the first time in a cestode species that lives in the peritoneal cavity of its host. The surface-membrane complex of plerocercoids was lost for the most part after conventional preparation for electron microscopy but could be completely retained by improved fixation using osmium tetroxide plus potassium ferrocyanide. Furthermore, one type of vesicle in the tegumental syncytium of plerocercoids has been found to be enclosed by at least two membranes, which might indicate that these vesicles contribute to the renewal of the surface-membrane complex. Adult Ligula intestinalis removed from the gut of the final host Anas platyrhnychos or obtained by in vitro transformation exhibited a single surface membrane and lacked double membrane vesicles. The elongate electron-dense caps of the microtriches of plerocercoids were replaced by short caps in the course of worm maturation. Thus, the tegumental surface of this parasite is fundamentally altered following the change in its environment from the peritoneal cavity of the intermediate host to the intestine of the final host.

Animals↗
PubMed1989

Spermatogenesis and the fine structure of the mature spermatozoon in the free proglottis of Trilocularia acanthiaevulgaris (Cestoda, Tetraphyllidea).

Spermatogenesis and the structure of the mature spermatozoon of Trilocularia acanthiaevulgaris have been studied by light microscopic histochemistry and transmission and scanning electron microscopy. The primary spermatogonia occupy the periphery of the testis and undergo four mitotic divisions; incomplete cytokinesis results in two secondary, four tertiary and eight quaternary spermatogonia and sixteen primary spermatocytes. The quaternary spermatogonia and successive stages develop in a plasmodial rosette with their nuclei at the periphery and connected to the cytophore by cytoplasmic bridges. The primary spermatocytes undergo two meiotic divisions, resulting in 64 spermatids that develop into spermatozoa. Intranuclear synaptonemal complexes in primary spermatocytes confirm the first meiotic division. The onset of spermiogenesis is marked by an elongation of the spermatid nucleus and the appearance of "arching membrane-bound clefts" (after Rosario 1964) that delimit the differentiation zone. The latter contains a pair of axonemes with their associated basal bodies and rootlets and, as it extends, the nucleus migrates into it. At first, the axonemes grow at right angles to the extension, but during development they rotate through 90 degrees and come to fuse with the cytoplasmic extension. The mature spermatozoon has a broad head region, a middle piece and a narrow tail region. It consists of a highly coiled nucleus, paired axonemes of the 9 + 1 pattern typical of platyhelminths, one of which extends the full length of the tail and the other ends part-way along the tail, particles of beta-glycogen and peripheral microtubules. A crested body spirals around the outside of the sperm body in the tail region. T. acanthiaevulgaris is placed in context within the phylogenetic schemes for cestodes based on sperm ultrastructure.

Animals↗
PubMed1989

Observations on the lipids of Oochoristica agamae (Cestoda).

An investigation of the lipids of Oochoristica agamae, an anoplocephalid cestode of the Agama lizard, was undertaken. Total lipids of the parasite accounted for 8.4% of the fresh weight; neutral lipids comprised 82.98% of the total, glycolipids, 5.01%, and phospholipids, 12.03%. The major lipid classes in O. agamae include triglycerides, cholesterol, phosphatidyl choline, and phosphatidyl ethanolamine. The 16- and 18-carbon fatty acids were predominant in the parasite. Hexadecenoic acid, usually found at low concentrations in the lipids of helminth parasites, was the most abundant of the 16-carbon fatty acids of O. agamae (notably in the neutral lipid fraction). Although octadecatrienoic acid occurred only in trace amounts in the intestinal contents of the host, significant amounts of this fatty acid were detected in the parasite. A lack of 20-carbon fatty acids was determined in the lipids of the host's intestinal contents and the neutral lipid fraction of the parasite. O. agamae is suspected to be capable of modifying fatty acids obtained from dietary sources by chain elongation.

Animals↗
PubMed1993

Electron immunogold labeling of regulatory peptide immunoreactivity in the nervous system of Moniezia expansa (Cestoda: Cyclophyllidea).

An electron immunogold-labeling technique was used in conjunction with a post-embedding procedure to demonstrate for the first time the ultrastructural distribution of the parasitic platyhelminth neuropeptide, neuropeptide F (NPF), in the nervous system of the cestode Moniezia expansa. Two axon types, distinguished by their populations of different-sized electron-dense vesicles, were identified. Immunogold labeling demonstrated an apparent homogeneity of PP, FMRFamide and NPF (M. expansa) antigenic sites throughout the larger dense-cored vesicles within the central nervous system. Triple labeling clearly demonstrated the co-localisation of immunoreactivities (IR) for NPF, PP and FMRFamide within the same dense-cored vesicles. The presence of NPF-IR within the vesicles occupying the perikaryon of the neuronal cell body indicated that the peptides had undergone post-translational C-terminal amidation prior to entering the axon. Antigen pre-absorption experiments using NPF prevented labeling with either PP or FMRFamide antisera, and the failure of these antisera to block NPF-IR supports the view that some, if not all, of the PP/FMRFamide-IR is due to NPF-like peptides.

Animals↗
PubMed1994

On the morphology of procercoids of the genus Proteocephalus (Cestoda, Proteocephalidea).

The morphology of larvae of four Proteocephalus species from copepod crustaceans as studied by scanning electron microscopy is described. Differences between species in the shape of the body and scolex as well as in the body size and relative position of suckers were revealed. In some species, a host-dependent variability in dimension indices and microthrix density was observed.

Animals↗
PubMed1994

Morphological and genetic comparison of two Proteocephalus species (Cestoda: Proteocephalidae).

Two Proteocephalus species, P. neglectus La Rue, 1911 and P. exiguus La Rue, 1911, parasites of salmonid and coregonid fishes, were compared morphologically, biometrically, and electrophoretically. The study revealed that the two taxa cannot be differentiated by the morphological criteria used. No fixed allelic difference was found. In all, 12 of 13 enzymes detected by isoelectric focusing exhibited virtually identical isoenzyme profiles in both species. Only in the glutamate oxaloacatate transaminase enzyme locus was a difference observed. The negligible differences in zymograms and morphology, including similar biometric variability of the taxa studied, suggest that the species could be conspecific.

Animals↗
PubMed1991

Ultrastructure of the excretory system of Trilocularia acanthiaevulgaris (Cestoda, Tetraphyllidea).

The fine structure of the excretory system in the juvenile (plerocercoid-like) form of Trilocularia acanthiaevulgaris is described. The flame cell bears a bunch of 50-70 cilia, which are anchored in the cytoplasm by means of basal bodies possessing striated rootlets. All the cilia in the "flame" are aligned in the same direction. The flame and duct cells are connected by interdigitating ribs of cytoplasm separated by a fibrous sheet. Both internal and external leptotriches are also present. The lumen of the excretory ducts is intracellular in origin. The apical surface of the cytoplasm lining the duct is convoluted and its surface area is further amplified by means of microvilli. The fine structure of the excretory system in this primitive tapeworm is compared with that described for other parasitic and free-living flatworms.

Animals↗
PubMed1999

Contributions to the phylogeny of the Cyclophyllidea (Cestoda) inferred from mitochondrial 12S rDNA.

A 314-bp fragment of the mitochondrial 12S rRNA gene from 21 cestodes species of eight families was synthesized by PCR with specially designed primers. These allowed amplification of parasite DNA without concomitant synthesis of host DNA. Phylogenetic trees were inferred from the sequence data using three methods (maximum parsimony, maximum likelihood, and Fitch-Margoliash). At the major nodes all three trees were similar. For the first time the genus Mesocestoides could be arranged into the Cyclophyllidea and a narrow relationship between the Mesocestoididae, Taeniidae, Hymenolepididae, Anoplocephalidae, and Dipylidiidae was shown. Members of the families Catenotaeniidae and a cluster of two families (Hymenolepididae and Dilepididae) form two monophyletic groups which derive prior to the remaining families of this phylogenetic study. A third and a fourth clear monophyletic group were formed by the Taeniidae and by the Mesocestoididae. A high degree of variation within the examined 304-bp fragment was observed between two isolates of Taenia taeniaeformis, supporting often discussed genetic heterogeneity within this species. In contrast, only one nucleotide exchange was found in 23 isolates of Echinococcus multilocularis of various geographic origin, indicating that this species is genetically homogenous.

Animals↗
PubMed2000

Otobothrium cysticum (Cestoda: Trypanorhyncha) from the muscle of butterfishes (Stromateidae).

On the basis of the tentacular armature, surface ultrastructure, and morphological measurements of plerocerci obtained from the musculature of butterfishes (Stromateidae), we corroborate an earlier proposal that Otobothrium crenacolle, a commonly reported trypanorhynch cestode from the northwestern Atlantic coast, is a junior synonym of O. cysticum. This action exemplifies at least an Atlantic Ocean and Indian Ocean distribution for O. cysticum. The infection in commercially important butterfishes shows that an otobothriid trypanorhynch may heavily infect fish flesh and influence the market value of some fish species yet also be restricted to the body cavity of other fish intermediate hosts. Infections of O. cysticum in the flesh of Peprilus burti (Gulf butterfish) and P. alepidotus (harvestfish) in the Gulf of Mexico has varied annually since 1970, with samples ranging in prevalence between 20% and 100% and in mean intensity between 1 and 3,500 or more plerocerci per fish. Comparative infections in P. burti from the Gulf of Mexico and P. triacanthus (butterfish) from the Atlantic Ocean demonstrate a present geographic difference in infections. The prevalence and mean intensity in 4 collections of butterfishes ranged from 9% to 98% of the fish and from 1 to 678 plerocerci in a subsample of tissue, respectively, with prevalent and heavy infections being observed in the Gulf of Mexico fish and relatively few individuals being infected with few worms in the Atlantic fish. A slight host response in the butterfishes involving some fatty infiltration and inflammatory infiltration was associated with the metacestode. In some larger fish, encapsulations were yellow, and in a few cases, worms had degenerated. This finding and an increase in intensity with fish weight suggest a continual accumulation of the worms in association with little host resistance.

Animals↗
PubMed2000

Ultrastructure studies of Proteocephalus longicollis (Cestoda, Proteocephalidea): transmission electron microscopy of scolex glands.

The ultrastructure of two types of secretory glands in the scolex of preadults of Proteocephalus longicollis is described for the first time in the present report. The gland cells contain extensive cisternae of granular endoplasmic reticulum and Golgi complexes, which participate in the production of secretory globules. Type I scolex glands produce electron-dense globules of various size. The secretory globules enter the secretory canal, openings of which were not observed in the preadults. The secretory product of type I was found at the inner sucker surface and in the tegument of the sucker edges. In addition, electron-dense globules in adult worms are secreted via an eccrine mechanism. Type II scolex glands are characterized by secretory globules of lower electron density and occur mainly in preadults. The electron-lucent, membrane-bound secretory globules are transported via microtubule-lined ducts opening to the exterior at the tegumental surface. Secretory globules of type II are released by an eccrine process.

Animals↗
PubMed2002

Comparative karyological analysis of three species of Bothriocephalus Rudolphi 1808 (Cestoda: Pseudophyllidea).

The diploid complements of mitotic metaphase plates of three species of Botriocephaluswere studied using conventional Giemsa staining and karyometric analysis. Botriocephalus claviceps and Botriocephalus gregarius showed a karyotype with 2n=14 chromosomes. All chromosomes of B. claviceps were biarmed, metacentric or meta-submetacentric. The two first pairs of homologues were markedly larger than the remaining elements and represented 48.62% of the total chromosome length. The karyotype of B. gregarius had similar metric values for the chromosomes, but clearly differed in the chromosome morphology of pairs 5, 6 and 7, which had terminally located centromeres. The diploid number 2n=12 was found in Botriocephalus scorpii. The karyotype consists of five pairs of metacentric and one pair of submeta-metacentric chromosomes. The possible pathways of karyotype evolution within Bothriocephalus spp. and their phylogenetic relations with the other karyologically studied groups in the order Pseudophyllidea are discussed.

Anguilla↗
PubMed2003

A molecular study of Eubothrium rugosum (Batsch, 1786) (Cestoda: Pseudophyllidea) using ITS rDNA sequences, with notes on the distribution and intraspecific sequence variation of Eubothrium crassum (Bloch, 1779).

The internal transcribed spacers (ITS-1 and ITS-2) of the ribosomal DNA (rDNA) of fish cestodes of the genus Eubothrium were sequenced. The ITS sequences of Eubothrium rugosum were determined and compared with previously analysed congeneric species, Eubothrium crassum and Eubothrium salvelini. The ITS-1 sequences of E. rugosum and E. crassum were 535 bp long, the length of E. salvelini ITS-1 was 536 bp. The ITS-2 region was found to be 403 bp in E. rugosum and E. crassum, and 401-402 bp in E. salvelini. The ITS-1 region of E. rugosum was closer to E. salvelini (identity 98.9-99.1%) than to E. crassum(97.9-98.1%), while the sequence similarity within the ITS-2 region was almost identical (97.5-98.0% for E. crassum; 97.7-98.3% for E. salvelini). Several restriction enzymes were found to be suitable for the differentiation of the three Eubothrium species by PCR-RFLP. The intraspecific sequence variation of E. crassum from different fish hosts (freshwater and marine) and European regions was very low, 0.2% for ITS-1 and 0.5% for ITS-2. Analysis of the ITS sequences of specimens from rainbow trout from three localities in Scotland revealed that both E. crassum and E. salvelini are present in this fish host.

Animals↗
PubMed2003

Ultrastructure of the early rostellum of Silurotaenia siluri (Batsch, 1786) (Cestoda: Proteocephalidae).

The neodermis of the whole early rostellum of Silurotaenia siluri (Batsch, 1786) bears filamentous microtriches. At the base, there are five to six irregular rows of hooks and spine-like microtriches. The rostellar hooks of S. siluri originate through the enlargement of microtriches. Electron-dense hook substance is deposited along the edges of the microthrix to form the hook blade and basal plate. The blade does not become hollow as in the cyclophyllidean cestodes. The basal plate of the hook, corresponding to the handle and the guard of Cyclophyllidea, is formed by the deposition of hook substance around the base of the microthrix. Within the centre of the base, only a narrow cleft-like core is occupied by distal cytoplasm. The hook bases are more deeply inserted into the distal cytoplasm, as the bases of the spine-like microtriches are localized on the rostellum below the rows of hooks. No hemidesmosomes, fixing the hook base to the basal lamina, are present. Eccrine gland cells and uniciliate and nonciliate sensory receptors of the primitive rostellum are described.

Animals↗
PubMed2003

Ultrastructure of spermiogenesis and the spermatozoon in the genus Joyeuxiella Fuhrmann, 1935 (Cestoda, Cyclophyllidea, Dipylidiidae): comparative analysis of J. echinorhynchoides (Sonsino, 1889) and J. pasqualei (Diamare, 1893).

This paper describes the ultrastructure of spermiogenesis and the mature spermatozoon of two Dipylidiidae cestodes, Joyeuxiella echinorhynchoides and J. pasqualei. In both species, spermiogenesis follows the type III described by Bâ and Marchand for the cyclophyllideans. Nevertheless, it is interesting to note the presence of striated roots associated with the centrioles. The spermatozoon presents the same ultrastructural features in J. echinorhynchoides and J. pasqualei. The apical cone in the anterior extremity of the sperm is more than 2.0 microm long in both J. echinorhynchoides and J. pasqualei. Both species present a single crest-like body, 150 nm thick in J. echinorhynchoides and 75 nm thick in J. pasqualei. The cortical microtubules are spiralled at an angle of 40-45 degrees to the spermatozoon axis in both Joyeuxiella species. A periaxonemal sheath and glycogen granules are also described in the mature sperm. We also describe, for the first time, the disposition of glycogen granules in two opposed and spiralled cords in cestodes and the formation of the periaxonemal sheath in the final stage of spermiogenesis.

Animals↗
PubMed2004

Allozyme analysis of genetic variation and polymorphism in Eubothrium salvelini and E. crassum (Cestoda: Pseudophyllidea) from alpine lakes.

The genetic structure of the most abundant species in the genus Eubothrium, E. crassum and E. salvelini, was studied by allozyme analysis in order to provide a consistent diagnosis for these morphologically similar species, as well as to assess their genetic relatedness. The proportion of fixed allelic differences (56.3%, 9 of 16 loci) between the species falls within the range accepted for valid species. A strict host specificity of E. crassum and E. salvelini for their typical host (lake trout, Arctic charr, respectively) was found in the French localities examined (Lake Annecy, Lake Bourget). For E. salvelini, polymorphism with the established allelic profile was found in the acid phosphatase (ACP) system. No significant deviation from the Hardy-Weinberg equilibrium expectations for ACP were found in either of the E. salvelini populations, which suggests predominantly cross-fertilization of these hermaphrodites. Analysis of the standardized variance in allelic frequencies demonstrated almost no among population differentiation (estimator theta of Fst = -0.03) between E. salvelini populations.

Animals↗
PubMed2004

Molecular systematics of several cyclophyllid families (Cestoda) based on the analysis of 18S ribosomal DNA gene sequences.

The sequences of the 18S small subunit ribosomal DNA of five species of cyclophyllidean cestodes from the families Davaineidae, Anoplocephalidae and Dilepididae were determined. A species of tetrabothridid was also sequenced. These 18S sequences were combined with other available eucestode sequences in GenBank. From the 1,838 sites in the alignment, 375 bp (20%) were excluded from the analysis due to alignment issues inferred by manual inspection. Phylogenetic trees were obtained by maximum parsimony, neighbour-joining distance and maximum likelihood methods. Analyses showed that Cyclophyllidea is monophyletic and separate from Tetrabothrius spp. Lyruterina nigropunctata, which is now included in the family Paruterinidae, is more closely related to davaineids of the genus Raillietina than Pseudidiogenes nana (Davaineidae). P. nana and Choanotaenia infundibulum (Dilepididae) derive from the Davaineidae (or Raillietininae). The two species of Taenia (T. parva and T. pisiformis) formed a monophyletic sister group to the Davaineidae and Anoplocephalidae. The systematics of the Paruterinidae have been problematic and our results suggest a review of this family including other species with paruterine organ located in other families. The position of the Idiogeninae as a subfamily in the Davaineidae is also reviewed.

Animals↗