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The distribution of acetylcholinesterase (AChE) in oncospheres and developing cysticercoids of Hymenolepis diminuta was examined. The enzyme was localized in the nervous system and in some non-nerve cells of these larvae. In oncospheres AChE was detected in hook muscles and in the binucleated medullar center that is known to enclose two neurons. At early developmental stages of the cysticercoids the enzyme was localized in the post-oncospheral hook muscles and in subtegumental muscle fibers of the cercomer. At medium and late stages of development the activity of AChE was detected in the developing nervous system and in two and, subsequently, in four populations of cells, which gradually spread over the whole internal wall of the cyst, thus forming a thin multilayer AChE-positive lining of the cyst cavity. Following withdrawal of the scolex the lining separates the parenchyma of the turned neck from the cyst tissues and remains AChE-positive during the whole life of the parasite, i.e. up to the death of the infected host. The role played by non-neural AChE associated with the cyst cavity lining is unknown, but seems to regulate both the transport of nutrients and minerals into the scolex and waste substances in the opposite direction.
The accumulation of neutral lipids in the cells predetermined to evolve into the cyst cavity lining in Hymenolepis diminuta cysticercoids is presented. The differentiation of these cells from the mesenchyma cells and the accompanying systhesis of lipids began in very young, blastula-shaped larvae. Both the number of the cells and the amount of their lipids increased gradually during further development of the parasites. In the pre-encystment stage of the cysticercoids the cells concentrated around the cavity of the prospective cyst. Following encystment, the scolex and the inverted neck became surrounded by a compact mass of the cells, which started using the stored lipids as a source of energy indispensable for the formation of the cyst tissues and of the definitive multilayer lining of the cyst cavity. No neutral lipids were detected in the mature 23-day-old cysticercoids as well as in the experimentally excysted scoleces. Beside a low level of uniformly distributed phospholipids apparently associated with cell membranes, no local accumulations of these substances were observed at any step of the development of the larvae. The utilization of neutral lipids proves both the presence of a lipase-type enzyme(s) and an operative β-oxidation pathway in the cells of the cysticercoids, the latter feature being highly indicative of oxidative metabolism of these larvae.
A total of 863 specimens of Gammarus spp. was examined for helminth parasites. The amphipods were collected in the summers of 1988-1990 from 5 places along the shore of the south-east Baltic. Five species of parasites were found: metacercariae of Maritrema subdolum, Spelotrema papillorobustum and Levinseniella propinqua, cysticercoids of Microsomacanthus abortiva and cystacanths of Polymorphus contortus.
The investigations covered 54 subsequent generations of Hymenotepis diminuta WMS „strain" obtained through the administration of 6 cysticercoids of tapeworm to Wistar strain rats and WAG alb. rats. The number of tapeworms at 2.5 months after the infection of rats ranged from 3 to 6, on the average 5.2. Taking into consideration the most important type 1p2a (one testis on the poral side and two testes on the aporal side), 0p3a, 1p3a and 2p1a proglottids a significant differences was found in the distribution of the numerousity of type 1p3a proglottids (P<0.05). This indicates a possibility of an unguided change of the numerousity of proglottids of this type in a period covering 54 subsequent H. diminuta generations bred in laboratory conditions.
In August 2007, 856 specimens of Echinogammarus tibaldii Pinkster et Stock, 1970 from the Lake Piediluco (Central Italy) were collected from 3 different sites and examined for larval helminths. Fourteen amphipods (1.63%) were infected with larvae of Lateriporus teres (Dilepididae) and one amphipod (0.12%) was infected with Microsomacanthus microsoma (Hymenolepididae). Adults of both species are known from waterfowl and gulls. The present results constitute new host records for both cestode species and the first finding of L. teres in Italy.
A total of 3,300 specimens of brine shrimps Artemia parthenogenetica from the Odiel Marshes, Huelva Province, SW Spain, were studied during several seasons of 2002 and 2003 for the presence of cestode infections. Cysticercoids were found in 26.8% of brine shrimps. Eight cestode species were recorded, i.e., Hymenolepididae: Flamingolepis liguloides (adults parasitic in flamingos) with prevalence (P) 18.5%, mean intensity (MI) 1.48 and mean abundance (MA) 0.28; F. flamingo (adults parasitic in flamingos), P 0.9%, MI 1.03, MA 0.01; Confluaria podicipina (adults parasitic in grebes), P 6.5%, MI 1.42, MA 0.09; Wardium stellorae (adults parasitic in gulls), P 0.2%, MI 1.00, MA 0.002; Dilepididae: Eurycestus avoceti (adults parasitic in waders and flamingos), P 2.7%, MI 1.08, MA 0.03; Anomotaenia sp., probably A microphallos (adults parasitic in waders), P 0.8%, MI 1.04, MA 0.01; A tringae (adults parasitic in waders), P 2.2%, MI 1.01, MA 0.02; Progynotaeniidae: Gynandrotaenia stammen (adults parasitic in flamingos), P 0.6%, MI 1.00, MA 0.01. The cysticercoids are described and accompanying illustrations are presented. This study provides the first record of Anomotaenia tringae in an intermediate host and the first records of C. podicipina, E. avoceti, A. tringae and G. stammeri in Spain.
Studies revealed the role of Artemia salina as intermediate host in the life-cycle of a cestode species parasitizing flamingos, i.e. Flamingolepis liguloides. Cysticercoids of this parasite were found for the first time in the Algerian populations of Artemia salina in winter of 2000 and 2001 in Chott Marouane and spring of 2003 in Sebkha Ez-Zemoul. The prevalence ranged between 10 and 33% for the two examined Artemia populations. The intensity of infection was 1–3 cysticercoids per individual. The abdomen was the most targeted site of infection (95% of the population of Sebkha Ez-Zemoul) followed by the thorax and the ovisac. Infected females were less fertile than uninfected ones (24.83 vs 43.70 cysts/brood) in Sebkha Ez-Zemoul or castrated in Chott Marouane.
Cysticercoids of two cestode species isolated from brine shrimps from the Mediterranean coasts of Spain and France are described. Fimbriarioides tadornae Maksimova, 1976 (adults known as parasites of Tadorna tadorna) was recorded from Artemia parthenogenetica and A. franciscana from Spain (Bras del Port and River Ebro Delta, respectively), and from A. franciscana from Aigues-Mortes, France (new geographical record). Branchiopodataenia gvozdevi (Maksimova, 1988) (adults known as parasites of Larus genei) was recorded from A. parthenogenetica (Bras del Port, Spain), A. salina (San Pedro del Pinatar, Spain) and A. franciscana (River Ebro Delta, Spain); this is the first record of the species in Europe. An illustrated key to cysticercoids of 12 cestode species from Artemia spp. from the Western Mediterranean is proposed.
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