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This is the first acute-intensity record of helminths parasitizing the subtropical krill Nyctiphanes simplex Hansen, 1911. We briefly describe the pathology of infection of Phyllobothriidae gen. sp. plerocercoids parasitizing N. simplex in the Gulf of California. Infection occurred with a very low prevalence (P = 0.06%, n = 1563 specimens), although acute-intensity exceeded several hundred plerocercoids crowding the hemocoel in one female host. Nyctiphanes simplex showed inflammatory response of hemocyte-based infiltration, nodule formation, and presumptive melanization. Remarkably, cestodes invade and supplant the gonad, causing atretic oocytes and severe tissue destruction in the gonad likely leading to castration and cell death in connective tissue of the infected organs suggesting that acute-intensity infection exceeds the krill's reaction capacity. Thus, Phyllobothriidae gen. sp. negatively affects the host by depleting its fitness, leading to total castration to prevent/block host reproduction.

The sensory organs in tegument of two trypanorhynchean species--Nybelinia surmenicola (plerocercoid) and adult Parachristianella sp. (Cestoda, Trypanorhyncha)--were studied with the aim of ultrastructural description and a comparative analysis. The Nybelinia surmenicola plerocercoid lacks papillae with sensory cilia on the bothria adhesive surface. We found an unciliated sensory organ within the median bothria fold. This unciliated free nerve ending contains the central electron-dense disc, three dense supporting rings, and broad root. The nerve ending locates in the basal matrix under the tegument. The tegument of N. surmenicola has a number of ultrastructural features which make it significantly different from other Trypanorhyncha: (i) the tegumental cytoplasm has a plicated constitution in a form of high apical and deep basal folds, (ii) numerous layers of the basal matrix are presented in the subtegument, and (iii) the squamiform and bristlelike microtriches N. surmenicola lack the base and the basal plate. In contrast, numerous ciliated and unciliated receptors were found in Parachristianella sp.: six types on the bothria and one type in the strobila tegument. Ultrastructural constitution of sensory organs in the form of ciliated free nerve endings as well as unciliated basal nerve endings of Parachristianella sp. has many common features inside Eucestoda. In comparison with other Trypanorhyncha, all Nybelinia species studied have less quantity of the bothrial sensory organs. This fact may reflect behavioral patterns of Nybelinia as well as phylogenetic position into Trypanorhyncha. Our observations of living animals conventionally demonstrate the ability of N. surmenicola plerocercoids to locomote in forward direction on the Petri dish surface. The participation of the bothrial microtriches in a parasite movement has been discussed.

The Spirometra erinacei casein kinase I (SeCKI) gene was cloned and expressed in Escherichia coli, and its characteristics were investigated in this study. The recombinant SeCP protein (rSeCKI) was purified. The vaccination of mice with rSeCKI induced the Th1/Th2-mixed type of immune response with Th2 predominant (high levels of IgG1). Western blotting analysis showed that rSeCP was recognized by the sera of plerocercoid-infected mice, and anti-rSeCP serum recognized the native SeCP protein of plerocercoid crude antigens. Transcription and expression of SeCP was observed at the plerocercoid and adult stages of S. erinacei. Immunolocalization identified SeCKI in the tegument and parenchymal tissues of plerocercoids and in the teguments of adults. SeCKI appeared to be essential indispensable for the S. erinacei development and survival in host, but its biological functions need to be further investigated.

Spirometra erinacei is a pseudophyllidean tapeworm which inhabits the intestines of cats and dogs. The infections are usually asymptomatic in these animals, but the infection of the plerocercoid larvae of the parasite, spargana, cause sparganosis in other vertebrates, including human. In this study, we identified a gene encoding the copper/zinc-superoxide dismutase of S. erinacei (SeCuZn-SOD) and partially characterized the biochemical and functional properties of the enzyme. The open reading frame of SeCuZnSOD was 465 bp that encodes 154 amino acids. The characteristic amino acid residues and motifs required for coordinating copper and zinc enzymatic function were well conserved. The genomic length of the SeCuZnSOD was 1,985 bp consisting of three exons that are separated by two introns. SeCuZnSOD is a typical cytosolic form which shares similar biochemical properties, including broad pH optima and inhibition profile by KCN and H(2)O(2), with cytosolic Cu/Zn-SODs of other organisms. SeCuZnSOD was functionally expressed in both S. erinacei plerocercoid larvae and adult worms, and its expression level was significantly increased when the plerocercoid larvae were treated with paraquat. The enzyme may play essential roles for survival of the parasite not only by protecting itself from endogenous oxidative stress, but also by detoxifying oxidative killing of the parasite by host immune effector cells.

This study was undertaken to identify genes involved in the growth and development of Spirometra erinacei larvae, an intestinal tapeworm of cats and dogs, within the final host. The differential protein expression at three different stages of S. erinacei, the plerocercoid larvae, 8-day-old juveniles, and adults, was compared using two-dimensional electrophoresis. Specifically or highly expressed proteins in juvenile worms were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MS)/MS. The proteome map of larvae showed fewer protein spots than juveniles or adults, whereas juveniles or adults revealed a similar protein expression profile. Eight juvenile-specific and five upregulated proteins of juveniles were identified and matched to proteins of known biological functions. These were grouped into several categories of functionally related proteins: DNA/RNA metabolism, cell trafficking, cytoskeleton, protein processing and degradation, energy metabolism, and oxidative stress. Our results give an overview of the growth and development mechanisms of cestodes within the final host and extend our understanding of parasite biology in the host-parasite relationship.

In cestode parasites, calcareous corpuscles are thought to be associated with a number of intracellular physiologies by regulating the trafficking of mineral components. We previously separated these particular components by Ficoll, and their binding proteins of 10 kDa and 35 kDa in the Spirometra mansoni plerocercoid (sparganum). In the present study, we purified a 10 kDa protein employing octyl-Sepharose CL-4B affinity chromatography. Anti-serum raised against the purified protein showed specific reactions to the calcareous corpuscles of the worm section by immunohistochemistry, and recognized the 10 kDa protein by immunoblotting.

Sixty specimens of the “cururu” toad, Rhinella icterica (Spix 1824) (Bufonidae), were collected in Campo Belo do Sul, State of Santa Catarina, Brazil, between May 2009 and January 2011, and were examined for the presence of helminth parasites. Nine species of adult helminths were found: Catadiscus cohni, Rudolphitrema rudolphii, Cylindrotaenia sp., Rhabdias fuelleborni, Strongyloides sp., Cosmocerca rara, Cosmocerca brasiliensis, Aplectana elenae, and Oxyascaris sp., in addition to an unidentified adult nematode species. Females of cosmocercid nematodes, proteocephalan plerocercoid, and acanthocephalan cystacanth were found but not identified for lack absolute of taxonomic characters. The sex of the anurans had no influence on prevalence, abundance, and richness of helminth species. Length and body mass of hosts did not influence the prevalence and richness of helminths, while the abundance of R. fuelleborni was significantly correlated with both parameters.

To investigate the mechanism by which liver weight increases during plerocercoid infections as well as the possible existence of a hepatocyte-growth-factor (HGF)-like substance in the serum of mice infected with Spirometra erinacei plerocercoids, liver DNA synthesis was measured in vivo and in vitro. Infection with S. erinacei plerocercoids significantly stimulated DNA synthesis in mouse parenchymal hepatocytes prior to the increase in liver weight, at least partly by stimulating the induction of the salvage pathways of pyrimidine biosynthesis. Furthermore, infected mouse serum directly stimulated DNA synthesis in cultured mouse parenchymal hepatocytes. These results suggest that an HGF-like substance is present in the serum of mice infected with S. erinacei plerocercoids.

Tetrathyridia of Mesocestoides sp. (Platyhelminthes: Cestoda) were collected from the body cavities of Apodemus sylvaticus (Rodentia: Muridae) in Murcia, Spain, and processed by routine microscopical and histological techniques, including examination with brightfield, phase-contrast, and differential-interference-contrast optics. All specimens examined had solid hindbodies (i.e., lacked a primary lacuna), thus conforming to the plerocercoid metacestode type. The vast majority of tetrathyridia were highly aberrant, often lacking a scolex, varying greatly in body size, and exhibiting buds or duplexed body forms indicative of asexual proliferation. All of the aberrant forms, including those with normal scoleces and apparent absence of proliferation, possessed anomalous multi-lobed invaginations of the hindbody tegument, which were attached at many points to abnormally dilated excretory ducts. The tegumental and excretory epithelia were joined basally, but did not share a common lumen. These abnormal connections between these aberrant tegumental modifications and the abnormally dilated excretory ducts have not been described previously for any metacestode. This report contributes to understanding previously published reports of abnormalities in other plerocercoid metacestodes, including Mesocestoides spp. and diphyllobothriidean spargana.

Concentrations of heavy metals (Cu, Fe, Zn, Mn, Cr, Pb and Cd) in some organs of tench and tissues of its parasite found in Kovada Lake (Turkey) were analyzed using atomic absorption spectrophotometry and subsequently compared with the data from sediments and water. Only Cu, Fe, Zn and Mn were detected in water, sediment, plerocercoids of Ligula intestinalis and fish samples, while levels of Cr, Pb and Cd were below the detection limits. Four elements were found at higher concentrations in the plerocercoid than in different fish tissues (muscle, liver and gill), being 1.6-37.4 times higher than that measured in muscle, liver and gill. Significant positive (for Cu) and negative (for Fe, Zn and Mn) correlations were found between the quantity of heavy metals in water and tissues of L. intestinalis plerocercoids while there were significant positive (for Cu and Zn) and negative (for Fe and Mn) correlations between the quantity of heavy metals in bottom sediment and tissues of L. intestinalis plerocercoids. Cestodes were found suitable to reflect the amount heavy metals in sediments, providing more reliable information about the actual pollution of the reservoirs.

The ultrastructure of the papillae and presumed sensory receptors in the tegument of the scolex of Gymnorhynchus gigas plerocercoid were investigated by scanning and transmission electron microscopy. Four distinct types of putative sense receptor (including three uniciliated and one nonciliated) are described for the first time in G. gigas, and this investigation is the first detailed ultrastructure study of tegumental receptors carried out in trypanorhynch cestodes. Microtriches arranged in clusters with a dome-shaped pattern seemed to be papillae that contained a ciliated sensory receptor (type I). The density of these papillae was greater in the center of the bothridial adherent surface near the tentacle orifice than in the lateral margins of the bothridia or in the pars post-bothridialis. The type I receptor is characterized by a long cilium anchored in the nerve bulb by a dense basal body but lacks rootlets. The bulb contains one or two electron-dense collars, numerous electron-lucent neurovesicles, and some mitochondria. The type II receptor presents a short cilium retracted into an invagination of the tegument that arises from the basal body. The bulb contains one electron-dense collar and numerous electron-lucent vesicles, but the rootlets are absent. The type III receptor is also a ciliated receptor embedded in a bulb wider than that of types I and II, and it differs from type II in that it possesses two electron-dense collars and small rootlets associated with the basal body. No electron-lucent vesicle was found in the bulb of this type III receptor. The type IV receptor is a nonciliated receptor localized under the surface with no contact to the outside. It consists of a flattened bulb that contains two electron-dense collars and striated rootlets associated with a band of microfilaments. A comparison of the ultrastructural features of receptors in different cestodes is presented.

The present report demonstrates that the Gymnorhynchus gigas plerocercoid possesses various types of endo- and exoproteases with activity against general (azocoll, azocasein, and azoalbumin) and specific substrates (elastin, keratin, collagen, hemoglobin, fibrinogen, plasma, and immunoglobulin G). The activity against collagen is principally due to a 24-kDa collagenase with an isoelectric point of 7.5 and without isoforms or sugar residues. Moreover, its high degree of proteolytic activity against collagen under conditions similars to those encountered by the parasite in its hosts (pH and temperature) and its similarity to metallo- and cysteine proteases (the principal protease types implicated in degradation of tissues) suggests the importance of this molecule as a lytic enzyme principally implicated in penetration processes across the teleost muscle or/and into the gastrointestinal system of elasmobranch fishes as well as in molting processes.

The tegumental topography of the plerocercoid of Gymnorhynchus gigas is described for the first time. The surface features were examined by scanning electron microscopy. Eight different types of microthrix pattern were found. Differences in the shape and density of microtriches depend on their location. A unique morphological feature is reported herein, namely, filamentous microtriches that were arranged in clusters with a dome-shaped pattern when the bothridial surface was relaxed but sunk into a crater when the bothridial surface was contracted. In contrast to other trypanorhynchan cestodes, palmate microtriches are not found on the tegument of this plerocercoid. The microtriches on the caudal extension gradually increased in length with growing distance from the blastocyst, which showed short knob-like structures. These structures developed into elongated filiform microtriches on the posterior region of the caudal extension.

The gland cell and the tegument of the Spirometra erinacei plerocercoid following parasite migration in hamsters were observed by electron microscopy. Gland cells released secretory granules mainly into the frontal pit during each stage of migration. The density of the perinuclear secretory granules decreased markedly just after parasite penetration through the host intestinal wall. Therefore, gland cells seem to play an essential role in penetration. During migration in the host, lipid-like droplets appeared in the subtegumental cells and tegument and increased in number and size during migration in the abdominal cavity, but they had disappeared from plerocercoids recovered from subcutaneous tissues. Myelin-like bodies also occurred in the tegument, subtegumental cells and medullary matrix; they were released directly through the tegument into the frontal pit. Discoidal bodies gathered in the distal part of the tegument, where filamentous microtriches appeared in regions from which microtriches had been peeled off during penetration.

The localisation and distribution of the cholinergic and serotoninergic components of the nervous system in the plerocercoid, adult and free proglottis stages of the tetraphyllidean tapewormTrilocularia acanthiaevulgaris were determined by enzyme histochemical and immunocytochemical techniques. The central nerve ring (CNR) in the scolex contains two lateral ganglia and gives rise to five pairs of longitudinal nerve cords (LNC's; three lateral, two median). The nerve cords run posteriorly throughout the bodies of the plerocercoid and adult worms and the free proglottis. Nerves from the CNR and accessory lateral LNC's pass to the bothridia, where they give rise to extensive nerve plexuses. As the individual proglottides develop along the strobila, a small nerve ring forms at the anterior end of each proglottis; within the nerve ring, distinct bilateral ganglia develop prior to the release of the proglottis. All ten LNC's are present in the free proglottis. The genital atrium and cirrus sac are innervated by cholinergic and serotoninergic elements. The cholinergic nervous system predominates in the CNS within the scolex, whereas there is a larger population of 5-HT-immunoreactive nerve cells associated with the LNC's and segmental ganglia along the strobila and within the free proglottis.

Young, male ICR mice were given tap water or distilled water containing 200 mg/l propylthiouracil (PTU) and were then infected with 10 plerocercoids of Spirometra erinacei to investigate the effect of plerocercoid infection on thyroid hormone in their hosts. Plerocercoid infection stimulated growth in PTU-induced hypothyroid mice as if they had never received PTU treatment: there were increases in weight in the liver, skeletal muscle, and spleen, as well as enhancement of the head and body length, in spite of a greater decrease in serum T4 levels than was observed in PTU-treated controls. Furthermore, the intact mice infected with plerocercoids showed a decrease in serum T4 levels as well as in the concentration of T4-binding globulin. These observations suggest that the growth stimulation and the decrease in concentrations of serum T4 and T4-binding globulin associated with plerocercoid infection in mice probably resulted from secretion of a growth hormone-like substance produced by plerocercoids of S. erinacei.

This study was performed to investigate the mechanism involved in a decrease in the serum glucose of golden hamsters infected with plerocercoids of Spirometra erinacei. The concentration of glucagon, the activity of glucose-6-phosphatase in the liver, and the in vivo incorporation of 2-deoxy-D-[1,2-3H]glucose into various organs increased in plerocercoid-infected hamsters compared with controls. Furthermore, the serum from the plerocercoid-infected hamsters enhanced the in vitro incorporation of [U-14C]glucose into adipose tissues, compared with control serum. The serum levels of immunoreactive insulin and somatomedin associated with nonsuppressible insulin-like activity in experimental animals, however, were not significantly different from those in controls. Therefore, we conclude that the decrease in serum glucose associated with plerocercoid infection is not the result of a decrease in gluconeogenesis, but the result of an increased utilization of glucose in the peripheral tissues.

Neurons immunoreactive to small cardiac peptide B (SCPb) occur in the scolex and neck region of adult Diphyllobothrium dendriticum. The localisation of the SCPb-IR neurons in the peripheral nervous system is very pronounced; they are closely associated to the bothridial musculature in the scolex. SCPb-IR neurons were not observed in plerocercoid larvae but appeared after cultivation in vitro at 37 degrees C for 30 h. Functional and developmental aspects of the SCPb-IR neurons are discussed.