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(1/109) Rainbow trout leucocyte activity: influence on the ectoparasitic monogenean Gyrodactylus derjavini.

The ectoparasitic monogenean Gyrodactylus derjavini from rainbow trout Oncorhynchus mykiss was exposed in vitro to macrophages isolated as peritoneal exudate cells or as pronephros cells from the host. Cells colonized the parasite especially in the mannose-rich regions in the cephalic ducts where ciliated structures were abundant. Opsonization with fresh serum, in contrast to heat-inactivated serum, enhanced colonization also on other body parts. The adverse effect of the activated macrophages towards G. derjavini was associated with a heat-labile component released from these cells to the culture medium. Analysis of substances released from the cells showed reactivity for a number of enzymes, complement factor C3, interleukin (Il-1) and reactive oxygen metabolites. Chemotaxis assays with pronephric leucocytes showed chemoattractants in G. derjavini, and the respiratory burst level of macrophages was slightly elevated due to parasite exposure. It is suggested that skin leucocytes contribute to an increased level of complement factors in the trout skin during the host response, whereby a hostile microenvironment for the parasites is created. In addition, the IL-1 production could affect mucous cell secretion and hyperplasia and add to the antiparasitic action of the epithelium. Likewise, reactive oxygen metabolites and various enzymes are likely to be involved in the skin response.  (+info)

(2/109) Helminth fauna of carnivores distributed in north-western Tohoku, Japan, with special reference to Mesocestoides paucitesticulus and Brachylaima tokudai.

In the winter of 1998-1999, we collected parasitological data from 54 wild carnivores in the north-western part of Tohoku region, Japan. These consisted of 38 martens (Martes melampus melampus), 14 raccoon dogs (Nyctereutes procyonoides viverrinus) and 2 foxes (Vulpes vulpes japonica). Collected helminth parasites were 11 nematode, 10 trematode, 3 cestode, and a single acanthocephalan species, including 5 hitherto unknown species for this research area or the mainland of Japan (Honshu). Mesocestoides paucitesticulus was for the first time recorded from martens as well as from carnivores distributed in Honshu. Brachylaima tokudai originally recorded from Urotrichus talpoides in the central part of Honshu was for the first time found from a raccoon dog.  (+info)

(3/109) Redescription of Tejidotaenia appendiculata (Baylis, 1947) (Cestoda: proteocephalidea), a parasite of Tupinambis teguixin (Sauria: teiidae) from South America.

The species Tejidotaenia appendiculata (Baylis, 1947), a parasite found in teju, Tupinambis teguixin is redescribed and a new diagnosis is provided. The species is characterized by the anterior position of the ovary and the peculiar shape of suckers. It is the first record of this species in Brazil.  (+info)

(4/109) Parasite-associated growth enhancement in a fish-cestode system.

Parasites impose an energetic cost upon their hosts, yet, paradoxically instances have been reported in which infection is associated with enhanced, rather than diminished, host growth rates. Field studies of these parasite effects are problematic, since the pre-infection condition of the hosts is generally unknown. Here, we describe a laboratory experiment in which the growth rate and body condition of 76 laboratory-reared three-spined stickleback fishes were examined before, during and after each fish was fed the infective stage of the parasitic cestode Schistocephalus solidus. Twenty-one of these fishes went on to become infected by the cestode. Fishes were individually housed and provided with an abundant food supply to eliminate the potentially masking effects of variable competitive ability. Infection occurred independently of fish gender, size, body condition or pre-exposure growth rate. After exposure to the cestode, infected fishes grew faster (excluding parasite weight) and maintained a similar or better body condition compared with uninfected fishes, despite developing enlarged spleens. The accelerated growth could not be explained by reduced gonadal development. This result, one of few demonstrations of parasite-associated growth enhancement in fishes, is discussed with respect to other such parasite systems.  (+info)

(5/109) Occurrence of Bothriocephalus acheilognathi in cyprinid fish from three lakes in the flood plain of the Yangtze River, China.

Cyprinid fish, Hemiculter leucisculus, Cultrichthys erythropterus and Culter dabryi, were sampled from Liangzi, Honghu and Tangxun lakes in the flood plain of the Yangtze River. The cestode Bothriocephalus acheilognathi Yamaguti, 1934 was found in the 3 lakes, but C. erythropterus sampled from Liangzi lake was found uninfected due probably to the small sample size. Findings of the cestode in the 3 lakes represent the first record of the parasite in the flood plain of the Yangtze River, indicating that B. acheilognathi may be distributed much wider in China than previously recognized.  (+info)

(6/109) Aspects of the ecology of proteocephalid cestodes parasites of Sorubim lima (Pimelodidae) of the upper Parana 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 Parana 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.  (+info)

(7/109) Aspects of the ecology of proteocephalid cestodes, parasites of Sorubim lima (Pimelodidae), of the upper Parana 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 Parana 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.  (+info)

(8/109) Complete sequence of the mitochondrial genome of the tapeworm Hymenolepis diminuta: gene arrangements indicate that Platyhelminths are Eutrochozoans.

Using "long-PCR," we amplified in overlapping fragments the complete mitochondrial genome of the tapeworm Hymenolepis diminuta (Platyhelminthes: Cestoda) and determined its 13,900-nt sequence. The gene content is the same as that typically found for animal mitochondrial DNA (mtDNA) except that atp8 appears to be lacking, a condition found previously for several other animals. Despite the small size of this mtDNA, there are two large noncoding regions, one of which contains 13 repeats of a 31-nt sequence and a potential stem-loop structure of 25 bp with an 11-member loop. Large potential secondary structures were identified also for the noncoding regions of two other cestode mtDNAS: Comparison of the mitochondrial gene arrangement of H. diminuta with those previously published supports a phylogenetic position of flatworms as members of the Eutrochozoa, rather than placing them basal to either a clade of protostomes or a clade of coelomates.  (+info)