Parasitologia, Volume 4, Issue 3 (September 2024) – 3 articles

The prevalence of endoparasites associated with chaetognath abundance in the coastal waters of the Mexican Central Pacific was studied fortnightly from November 2010 to December 2011. A total of 35 (0.21%) out of 16,407 chaetognaths were found to be parasitized. Five out of twelve chaetognath species (Flaccisagitta enflata, F. hexaptera, Parasagitta euneritica, Serratosagitta pacifica, Zonosagitta bedoti) were found to be parasitized by nine endoparasitic taxa: Protists (two morphotypes), digenean metacercariae [Didymozoidae, Hemiuridae, Parahemiurus sp., Lepocreadiidae, Prosorhynchus sp. (Bucephalidae)], and cestodes (metacestodes) [Tetraphyllidea (two morphotypes)]. Parasagitta. euneritica and Z. bedoti were the most abundant chaetognath species, and Protist sp. 2 and Tetraphyllidea sp. 1 were the most abundant parasites. The highest prevalence for most of the endoparasite species occurred in June, and the values varied according to three hydroclimatic periods: stratified (S), semi-mixed (SM), and mixed (M). Eight non-infected chaetognath species, two parasitized chaetognaths (F. enflata and S. pacifica), and two parasites (Protist sp. 1 and Tetraphyllidea sp. 2) were associated with warm temperatures (S and SM periods); in contrast, P. euneritica, Z. bedoti, parasitized F. hexaptera, and the parasite Tetraphyllidea sp. 1 showed a strong local preference for cooler temperatures, high productivity, and high biomass conditions (M periods). We discovered the occurrence of the digenean Prosorhynchus sp. (Bucephalidae) parasitizing the chaetognath P. euneritica, and this is the first report of Prosorhynchus parasitizing chaetognaths worldwide. We also confirmed the presence of Lepocrediidae (metacercariae larval stage) infecting F. hexaptera, a parasite that had only been recorded infecting other chaetognaths of the Atlantic Ocean. The parasite diversity affecting the chaetognath populations of the Central Mexican Pacific coast likely differs between the offshore, outer slope areas, and the surveyed coastal system. Full article

The aim of this study was to evaluate the isolated and associated use of the nematophagous fungi Pochonia chlamydosporia (isolate VC4) as an ovicide and Duddingtonia flagrans (isolate AC001) as a predator in the control of Taenia saginata eggs. Viable T. saginata eggs were obtained by dissecting mature proglottids from a specimen. For the experimental assay, four groups were formed in microtubes, as follows: (G1—T. saginata eggs/control); (G2—100 T. saginata eggs + VC4); (G3—100 T. saginata eggs + AC001); (G4—100 T. saginata eggs + VC4 + AC001). All the groups were stored in a B.O.D. incubation chamber at a temperature of 27 °C for 15 days and then the contents of the microtubes were analyzed using an optical microscope with a 40x objective. At the end of the assay the treated groups (G2 to G4) showed ovicidal activity (destruction of eggs) compared to the control group (G1). The highest ovicidal percentage was observed in group G2 (eggs + VC4), with 43.3%. In groups G3 and G4 (combination of fungal isolates), the ovicidal percentages were 25.7% and 25.6%, respectively. The results of this study shed light on a new possibility for the combined use of different species of nematophagous fungi, which could be used in the future for environmental biological control of T. saginata eggs. Full article

Endocytosis is a quintessential feature of eukaryotes, and the emergence of endocytosis played a major role in the origin and evolution of eukaryotes. During the early evolution of eukaryotes, phagocytosis and the digestion of prey (i.e., bacteria) combined with the endocytosis of macromolecules opened a new source of nutrients beyond osmotrophy. Pathogenic and commensal protozoa have retained endocytosis as a major mechanism of nutrient acquisition even though, in theory, nutrients could be obtained from the host through osmotrophy. Nearly all pathogenic protozoa exhibit endocytosis and have lysosomal-like compartments that function as digestive vacuoles, and endocytosis appears to play a major role in the acquisition of nutrients. Cryptosporidium is a possible exception that may not exhibit endocytosis. Phagotrophy, however, is only observed in parasites of the intestinal lumen and appears to have been lost in blood and tissue parasites. Overall, the basic features of endocytosis and lysosomes are similar to other eukaryotes. Nonetheless, adaptation to the host has generated some novel features that are specific to certain protozoan lineages. Full article