[Light and electron microscopic studies of the histopathogenicity of Macracanthorhynchus hirudinaceus (Archiacanthocephala) in experimentally infected domestic swine]

Element concentrations in the archiacanthocephalan Macracanthorhynchus hirudinaceus compared with those in the porcine definitive host from a slaughterhouse in La Paz, Bolivia

Concentrations of lead and cadmium, determined by electrothermal atomic absorption spectrometry, and concentrations of the elements barium, cadmium, copper, iron, magnesium, manganese, nickel, lead, selenium and strontium, determined by inductively coupled plasma mass spectrometry, in the acanthocephalan Macracanthorhynchus hirudinaceus and its porcine final host, sampled at a slaughterhouse in La Paz, Bolivia, were compared. Inductively coupled plasma mass spectrometry analysis revealed that most of the elements were found at higher concentrations in the acanthocephalan than in different tissues of its host. The bioconcentration of elements in M. hirudinaceus compared with the host intestine, listed in order of decreasing values, was as follows: Cd > Pb > Ni > Sr = Cu > Mg > Se > Fe = Mn = Ba. Analysis by electrothermal atomic absorption spectrometry showed that M. hirudinaceus contained 85, 85, 56 and 24 times higher lead levels compared with hosts muscle, liver, kidney and intestine, respectively. The mean cadmium concentration of the parasite was 32 times higher than that of the liver and five times higher compared with porcine kidney. The metal distribution within the body of M. hirudinaceus was as follows: cement gland > testes > lemnisci > eggs = tegument for lead and lemnisci > testes > cement gland > tegument > eggs for cadmium. Therefore, the hypothesis that parasites excrete toxic metals with the shells of their eggs seems not to be valid for M. hirudinaceus. It is concluded, that not only eoacanthocephalans and palaeacanthocephalans parasitising fish, but also archiacanthocephalans from mammalian hosts, are able to bioaccumulate metals.

Ultrastructure of the spermatid and spermatozoon of Macracanthorhynchus hirudinaceus

The ultrastructure of the spermatid and spermatozoon of Macracanthorhynchus hirudinaceus (Archiacanthocephala) was studied by means of transmission electron microscopy. The flagellum and nucleus in the spermatid gradually expanded simultaneously. The karyoplasma of the spermatid transformed into dense inclusions and a multibarrel structure, which were also found in the spermatozoan body. The multibarrel structure was located close to the flagellum and consisted of many irregular microtubes. The flagellum of the developing spermatozoon was observed in a concavity of the spermatid nucleus. The microtubule arrangement of the flagellum was "9 + 2". No mitochondria or acrosome were observed in spermatozoa.

Autoradiographic and morphological investigations on the uptake and incorporation of tritiated lysin by acanthocephalans

Four palaeacanthocephalans and two eoacanthocephalans from fish were autoradiographically investigated for their in vitro uptake of tritiated lysin. All worms took up the labelled amino acid at their surface without showing a species-specific pattern. The tegument of the metasoma was more heavily labelled than the presomal tegument, suggesting that the worms predominantly absorb the nutrient from the food inside the host's gut in vivo. Within the metasomal tegument the nuclei revealed the most intense labelling. In the muscles the outer myogenic belt absorbed more radioactivity than did the enclosed cytoplasmic core. In female worms the ovarian balls and eggs that showed incomplete eggshell formation were highly labelled. In male worms the cement glands showed the most intense labelling of all organs inside the body cavity. We conclude that the investigated acanthocephalans require lysin for protein synthesis and for the coding of protein synthesis in the tegumental nuclei.

Autoradiographic and morphological studies on the uptake of the triglyceride [3H]-glyceroltrioleate by acanthocephalans

Two eoacanthocephalans, four palaeacanthocephalans, including the infective larvae of one species, and one archiacanthocephalan were exposed in vitro to a labelled triglyceride. The nutrient was almost exclusively incorporated by the tegument of the presoma. The uptake of [3H]-glyceroltriolete started at the anterior half of the presoma, followed by a consecutive labelling of the entire presoma tegument and the lemnisci. In the archiacanthocephalan, however, the general uptake was comparatively low. In the final host of the acanthocephalans, the absorbed nutrient must derive from the host's intestinal wall, injured by the parasite. In the eoacanthocephalans and the palaeacanthocephalans, the labelled nutrient was most intensively taken up by the tegument of the hooks. Inside the hook tegument, the basal membrane and the outer membrane form a labyrinth of entangling crypts and protuberances. In the surrounding proboscis tegument as well as in the neck tegument, the lipid seemed to be transported along these two membranes. In addition to its absorption by the presoma tegument, the labelled nutrient was intensively incorporated by the apical organ and the paired lateral organ of the eoacanthocephalan presoma and by the terminal part of the uterine endothelium of all female eoacanthocephalans and palaeacanthocephalans. The use of the nutrient by the parasites is discussed.