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At least 289 records · Page 16Linked to original sources
PubMed1991

Characterization of a high-affinity choline uptake mechanism in the cestode Hymenolepis diminuta.

Radiolabelled choline was taken up by tissue slices of the cestode Hymenolepis diminuta by a sodium-dependent and a sodium-independent mechanism. The sodium-dependent uptake was saturable, against a concentration gradient, displayed structural specificity, and was inhibited, in part, by hemicholinium-3. Kinetic analysis of the sodium-dependent choline uptake showed an apparent Kt = 2.0 microM and a Vmax = 0.146 pmol.mg-1 wet weight tissue.min-1, which is consistent with a high-affinity choline uptake (HAChU) mechanism. The rate of uptake or release of choline depended on the magnitude and direction of the sodium gradient, was diminished by high- or low-potassium, but was not chloride or sulphate dependent. A homoexchange mechanism for HAChU was not demonstrated. Evidence was obtained to suggest that HAChU or release of endogenous ACh is regulated by autoreceptors. The choline taken up by the HAChU mechanism was but slowly converted to ACh and other products.

Acetylcholine↗
PubMed2000

Aspects of the ecology of proteocephalid cestodes parasites of Sorubim lima (Pimelodidae) of the upper Paraná River, Brazil: I. Structure and influence of host's size and sex.

Between March 1992 and February 1996, 107 specimens of Sorubim lima were collected in the floodplain of the upper Paraná river. Ninety-five (88.78%) specimens were parasitized with at least one species of proteocephalid cestodes. 7,573 specimens of four different species were collected (average intensity 79.71 parasites/host): Paramonticellia itaipuensis Pavanelli & Rego, 1991; Nupelia portoriquensis Pavanelli & Rego, 1991; Spatulifer maringaensis Pavanelli & Rego, 1989 and Spasskyellina spinulifera Woodland, 1935. S. maringaensis was the most prevalent and abundant. There were three dominant species P. itaipuensis, S. maringaensis and N. portoriquensis) and one co-dominant species (S. spinulifera). The three environments (lotic, semilotic and lentic) in which collection was undertaken showed high similarity with regard to parasitic fauna. A high Simpson index value (0.359) indicates dominance tendency among species of parasites. Concerning S. maringaensis significant positive correlation was observed between parasite intensity and standard length of hosts. No species had negative correlation. With regard to S. maringaensis and N. portoriquensis prevalence was positive and significantly correlated with standard length of hosts. No species had negative correlation. In the case of S. maringaensis and N. portoriquensis influence of host's sex was noted on parasite intensity. There was no sex influence on parasite prevalence in any species.

Animals↗
PubMed2000

Aspects of the ecology of proteocephalid cestodes, parasites of Sorubim lima (Pimelodidae), of the upper Paraná River, Brazil: II. Interspecific associations and distribution of gastrintestinal parasites.

One hundred and seven specimens of Sorubim lima (Bloch & Schneider, 1801) were collected in the floodplain of the upper Paraná River, Brazil between March 1992 and February 1996. Ninety-five specimens (88.78%) were parasited by at least a species of proteocephalid cestode. 7,573 parasites specimens of four different species were collected (average intensity 79.71 parasites/host): Paramonticellia itaipuensis Pavanelli & Rego, 1991; Nupelia portoriquensis Pavanelli & Rego, 1991; Spatulifer maringaensis Pavanelli & Rego, 1989 and Spasskyellina spinulifera (Woodland, 1935). The two most prevalent species, Spatulifer maringaensis and Paramonticellia itaipuensis, were parasiting the entire gastrointestinal tract. Nupelia portoriquensis parasited only the anterior and posterior intestine of the host.

Animals↗
PubMed1996

Prolactin in the Cestodes, Taenia solium and Taenia hydatigena: an immunocytochemical study.

The demonstration of prolactin in cestodes, Taenia solium and Taenia hydatigena, was investigated by using immunocytochemical method. PRL immunoreactivity was widely distributed in the CNS and PNS in the worms. In the scolex PRL-IR perikarya occurred in the cerebral ganglia, around the basic area of the sucker and the rostral border region between the rostellum and the suckers with strong immunoreaction, distinctly in Taenia solium. A number of PRL-IR nerve fibres were observed in the main nerve cords, and a few fibres in the transverse nerve commissure. The holdfast musculature of the scolex was innervated by the PRL-IR fibres. A large number of PRL positive cells with processes and nerve plexuses were seen in the ootype/Mehlis' gland complex, oviduct, the duct of uterum, seminal receptacle and its associated duct, conspicuously in Taenia hydatigena. PRL-IR was evident in the wall of vas efferens of tests and vas deferens. A few PRL positive cells occurred in the medullary parenchyma amongst testes and sent their varicose processes to terminate to the testes. On the wall of the main excretory duct a few PRL-IR cells and fibres were seen.

Animals↗
PubMed1975

The metabolism of foreign compounds in the cestode, Moniezia expansa, and the nematode, Ascaris lumbricoides var suum.

1. The ability of the cestode Moniezia expansa and the nematode Ascaris lumbricoides var suum to metabolize foreign compounds has been assessed. 2. Both species were unable to oxidase aldrin, aniline, biphenyl, butylbenzene and nitrobenzene or to demethylate aminopyrine, and 4-nitroanisole. 3. M. expansa and A. lumbricoides var suum readily induced 4-nitroanisole, nitrobenzene, 4-nitrobenzoic acid and 4-nitrophenol to the corresponding amines. Azobenzene, dimethylaminoazobenzene, and 1,2-dimethyl-4-(4-carboxyphenylazo)-5-hydroxybenzene were also reduced. 4. Hydrolysis of esters, acetanilide, acetylsalicylic acid, aryl sulphates and aryl phosphates took place readily. However, beta-glucuronides were not hydrolysed. 5. The following reactions were not detected in either species: phosphate, sulphate, beta-glucuronide or beta-glycoside conjugation of phenolic compounds; acetylation of amino compounds, or the formation of glycine conjugates with 4-aminobenzoic acid or benzoic acid. 6. Male nematodes showed a higher rate of drug metabolism than female nematodes.

Acetanilides↗
PubMed1979

Some properties of the sulphoxidases and sulphoxide reductases of the cestode Moniezia expansa, the nematode Ascaris suum and mouse liver.

1. The anthelmintics bithionol, phenothiazine, albendazole and fenbendazole were oxidized to sulphoxides by enzymes in the cytosol of the proglottids of the cestode Moniezia expansa and the cytosol of the intestinal epithelial cells of the nematode Ascaris suum. Enzymes in these tissues were also able to reduce these sulphoxides to the thioethers in the absence of oxygen. 2. Sulphoxidation and sulphoxide reduction also occurred in mouse liver enzyme preparations. About 20% of the sulphoxidation activity was not associated with microsomes and was not inhibited by CO; about 50% of the reductase activity was found in the microsomes. 3. The pH optima for sulphoxidases from both helminths were in the range 7.0--7.2, and both required NADH or NADPH for activity. Low molecular weight thiols and flavins did not affect sulphoxidation. Enzyme activity was inhibited by 0.1 mM Cu2+, Hg2+, Cd2+ or Zn2+ and by p-chloromercuribenzoate or N-ethylmaleimide. 4. Both helminth sulphoxide reductases displayed pH optima in the range 1.2--7.4, and required NADH or NADPH for activity. Oxygen inhibited the reductases.

Animals↗
PubMed1968

Studies On The Parasitic Helminths Of Korea: III. Nematodes And Cestodes Of Rodents.

A survey for nematode and cestode parasites of rodents in Korea has been carried out at the areas of Chulwon, Kumwha, Pochon, Paju and Chungpyong, Kyunggi-Do. A total of 300 rodents of seven species was examined, comprising of 219 A. agrarius, 33 R. norvegicus, 8 R. alexandrinus, 14 Mus musculus yamashinai, Microtus fortis pellceus, 21 Crocidura russula and a Cricetulus trition nester. The following fifteen species belonging to thirteen genera were identified. NEMATODA: Heterakis spumosa, Syphacia obvelata, Nippostrongylus muris, Protospirura muris, Capillaria hepatica, Capillaria sp., Heligmosomum sp., Heligmosomoides sp., Rictularia sp. and Gongylonema sp. CESTODA: Hymenolepis nana, Hymenolepis diminuta, Raillietina coreensis, Paranoplocephala sp. and Cysticercus fasciolaris(the larva of Taenia taeniaeformis).

Journal Article↗
PubMed1984

Distribution of cestodes in the digestive tract of Indian Hill-stream fishes.

The distribution of Bothriocephalus sp., Guptaia sp., Mackiewiczia sp., Polyonchobothrium sp., Ptychobothrium sp., and Senga sp. in the alimentary tract of nine Indian hill-stream fishes are described. Though the region around pyloric sphincter was preferred by most cestodes, Senga sp. enabled its existence even in the latter part of intestine apparently because of its well developed adhesive apparatus on scolex.

Journal Article↗
PubMed1976

Two tetraphylidean cestodes from the freshwater stingray Potamotrygon magdalenae Dumeril 1852 (Chondrichthyes: Potamotrygonidae) from Colombia.

Two new tetraphyllidean cestodes are described from the freshwater stingray Potamotrygon magdalenae from Colombia. The new genus Potamotrygonocestus is proposed for P. magdalenensis, which differs from Pedibothrium by having a bilobed rather than X-shaped ovary, and simple rather than bifid hooks. It further differs from Pachybothrium hutsoni by having bothridial hooks inserted immediately posterior to an accessory sucker rather than inserted in the middle of a thick muscular pad. Potamotrygonocestus magdalenensis is unique among known tetraphyllideans by possessing vitellaria which are compact, cylindrical bands in the lateral portions of the middle of the proglottid. The second new species, Rhinebothrium moralarai, resembles R. scorzai by having its genital pore and terminal genitalia at the ovarian level, greatly reduced poral ovarian lobes, and by parasitizing a freshwater stingray. It differs from R. scorzai in number of bothridial loculi, testes per proglottid, and proglottids per strobila; by having quadrate rather than canoe-shaped bothridia; and by parasitizing Potamotrygon magdalenae rather than P. hystrix.

Animals↗
PubMed1975

Characterization of nucleoside transport in hymenolepidid cestodes.

Three species of cestodes, Hymenolepis diminuta, H. citelli, and H. microstoma, were shown to transport nucleosides by a mediated process. In H. diminuta the Ki values of various competitive inhibitors led to the conclusion that at least 2 different loci are involved in the transport of nucleosides. One of these loci has greater specificity for the purine nucleosides, the other for pyrimidine nucleosides. No significant difference was observed in their affinity for ribo- or deoxyribonucleosides, although thymidine was slightly less effective as an inhibitor of ribonucleosides than was uridine. Transport by the pyrimidine nucleoside locus was stimulated by thymine, but not by hypoxanthine, whereas transport by the purine nucleoside locus was stimulated by hypoxanthine but not by thymine. Preloading the worms with thymine gave less stimulation of transport than did the presence of eoxgenous modulator. Efflux of previously accumulated nucleoside was not blocked by the presence of exogenous modulator. The presence of exgenous thymine enhanced the incorporation of uridine into the nonextractable pool. Thymine also stimulated uracil transport in H. citelli, but not in H. microstoma, and had no effect on uridine transport in either of these species. The results of transport and modulator studies on H. diminuta grown in hamsters were not different from the results with worms grown in rats indicating that the regulatory effects observed were an inherent function of the parasite and not the host.

Adenine↗
PubMedDate not supplied

[Brachylepis gen. n.--a new genus of cestodes (Cyclophyllidea: Hymenolepididae) from shrews in Siberia and the Far East].

A new genus Brachylepis gen. n. hymenolepididean cestodes associated with common shrews (Sorex) in Siberia and Russian Far East is created. These genus includes three species removed from the genus Mathevolepis: Brachylepis morosovi (Karpenko, 1994) comb. n. (type species), B. sorextscherskii (Morosov, 1957) comb. n. and B. triovaria Karpenko, 1990) comb. n. The new genus is characterized by the gradual strobila with a little number of segments, unarmed scolex with apical glandular organ, by lack of internal seminal vesicle and differential seminal receptacle, by form of uterus as horse shoe in young worms and buble-like in mature worms. A tendency of inverse proportional dependence between the number of uterus segments in the strobila and the number of hexacanths in the uterus has been noticed. The table of differential characters for the species of the genus Brachylepis is proposed.

Animals↗
PubMedDate not supplied

[The finding of a cestode in the little auk Alle alle on Franz Josef Land].

One of 14 dovekeys (Alle alle) investigated in August 1993 on Hooker Island (Franz Joseph Land) was found to harbour a single specimen of an early immature dilepidid cestode attributed as Alcataenia sp. The rostellum bears a double crown of 22 hooks, 0.025-0.027 mm in length. Except Threlfall (1971) there was no information concerning dovekey's parasites.

Animals↗
PubMedDate not supplied

[About the fauna of the cestode family Hymenolepididae from ducks of Chukotka: on the validity of the genus Echinatrium].

Four species of the genus Echinatrium Spassky et Jurpalova, 1965 are redescribed. The material was collected from ducks of the Chaunskaya lowland (Chukotka). Morphological study of genital apparatus in cestode species found was carried out. According to the priority rule, it is suggested that the genus Monosaccanthes Czaplinski, 1967 is a junior synonym of the genus Echinatrium.

Animals↗
PubMedDate not supplied

[Some peculiarities of the ultrafine structure of the neurons of the cestode Pelichnibothrium speciosum (Monticelli, 1889) (Cestoda: Tetraphyllidea)].

In the scolex ganglia of the cestode Pelichnibothrium speciosum uni - and multipolar neurons can be found. Their neuroplasm is rich in free ribosomes. The ergastoplasmas membranes are frequently arranged in compact finger print-like structures. The nerve cells processes form tight junctions which cannot be interpreted as synaptic contacts.

Animals↗
PubMed1998

Ultrastructural observation on the transformation of the spermatozoon in spermatogenesis of Taeniid cestodes.

AIM: To study the transformation of taeniid spermatozoon during spermatogenesis on the ultrastructure level. METHODS: Transmission electronmicroscopy. RESULTS: This paper was the second part of the ultrastructural observations on the spermatogenesis in Taeniid cestodes: The transformation of the spermatozoon. The 64-spermatid-plasmodium was generated from the secondary meiosis of the 32 rose-like secondary spermatocytes. The transformation of the spermatozoon was a complex process. Firstly, both the cytoplasm and nucleus of the spermatid elongated while the cytoplasm increased and connected to the cytoplasmic mass (cytophore). Secondly, the chromatins of nucleus polymerized to a thread-bundle-like structure. Finally, it detached from the cytoplasm mass and became a mature spermatozoon. The mature spermatozoon was a thread-like structure, about 16.2-18.6 microns in length and 0.35-0.45 micron in diameter. There were two structurally distinct parts: the part with the nucleus was the head and the part without the nucleus was the tail. The head measured about 5-6 microns in length, 1/3 of the total body length and contained an elongated nucleus which twined around the axoneme without mitochondria. The tail was about 11.2-16.6 microns in length. Throughout the core of the tail was an axoneme with typical "9 + 1" structure. The anterior of the tail, just behind the head, were some mitochondria, about 1.6-1.7 microns in total length which twined around the axoneme. The posterior of the tail contained only an axoneme. In cross-section of the spermatozoon, about 46 microtubules were beneath the plasma membrane. CONCLUSION: The transformation of the spermatozoon is a very complex process.

Animals↗
PubMed1975

Functional significance of non-specific esterase and its involvement in the excretory mechanism of trematodes, cestodes and nematodes.

The distribution of non-specific esterase in the excretory canals of nematodes, cestodes and trematodes is described. In all the cases the excretory canals are intensely positive, except in Dioecocestus fevita where the reaction is mild. In most of the cases the reaction is observed in the form of small granules, distributed throughout the canal. The distribution of the enzyme has been correlated with the excretory functions of these parasites.

Animals↗