Parasitic Protists: Diversity of Adaptations to a Parasitic Lifestyle (original) (raw)
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Hide-and-Seek: A Game Played between Parasitic Protists and Their Hosts
Microorganisms, 2021
After invading the host organism, a battle occurs between the parasitic protists and the host’s immune system, the result of which determines not only whether and how well the host survives and recovers, but also the fate of the parasite itself. The exact weaponry of this battle depends, among others, on the parasite localisation. While some parasitic protists do not invade the host cell at all (extracellular parasites), others have developed successful intracellular lifestyles (intracellular parasites) or attack only the surface of the host cell (epicellular parasites). Epicellular and intracellular protist parasites have developed various mechanisms to hijack host cell functions to escape cellular defences and immune responses, and, finally, to gain access to host nutrients. They use various evasion tactics to secure the tight contact with the host cell and the direct nutrient supply. This review focuses on the adaptations and evasion strategies of parasitic protists on the exampl...
Protist, 1999
The World Wide Web is a true revolution in communication. In regard to the study of protists, the web has a plethora of informational web sites. In this Protist News, I would like to briefly describe an assortment of interesting and useful sites. My list is illustrative and critical rather than all-inclusive, so please forgive me if I fail to include your favorite site or even your own site. Unfortunately this article as journal text is not on-line and therefore cannot utilize the full power and depth of hyperlinks, but I will list the URL's and you must then type them into your browser to link to them. If you get tired typing and prefer using a browser to be able to click directly to the various sites, this article will also be available on-line at the Protist web site (
Carolina-Host-Parasite Interaction Parasite-Derived and -Induced.pdf
Parasitic protozoa are among the most important pathogens worldwide. Diseases such as malaria, leishmaniasis, amoebiasis, giardiasis, trichomoniasis, and trypanosomiasis affect millions of people. Humans are constantly threatened by infections caused by these pathogens. Parasites engage a plethora of surface and secreted molecules to attach to and enter mammalian cells. The secretion of lytic enzymes by parasites into host organs mediates critical interactions because of the invasion and destruction of interstitial tissues, enabling parasite migration to other sites within the hosts. Extracellular matrix is a complex, cross-linked structure that holds cells together in an organized assembly and that forms the basement membrane lining (basal lamina). The extracellular matrix represents a major barrier to parasites. Therefore, the evolution of mechanisms for connective-tissue degradation may be of great importance for parasite survival. Recent advances have been achieved in our understanding of the biochemistry andmolecular biology of proteases from parasitic protozoa. The focus of this paper is to discuss the role of protozoan parasitic proteases in the degradation of host ECM proteins and the participation of thesemolecules as virulence factors.We divide the paper into two sections, extracellular and intracellular protozoa.
A Novel Clade of Protistan Parasites near the Animal-Fungal Divergence
Proceedings of The National Academy of Sciences, 1996
Sequences of nuclear-encoded small-subunit rRNA genes have been determined for representatives of the enigmatic genera Dermocystidium, Ichthyophonus, and Psorospermium, protistan parasites of fish and crustaceans. The small-subunit rRNA genes from these parasites and from the ``rosette agent'' (also a parasite of fish) together form a novel, statistically supported clade. Phylogenetic analyses demonstrate this clade to diverge near the animal-fungal dichotomy, although more precise resolution is problematic. In the most parsimonious and maximally likely phylogenetic frameworks inferred from the most stably aligned sequence regions, the clade constitutes the most basal branch of the metazoa; but within a limited range of model parameters, and in some analyses that incorporate less well-aligned sequence regions, an alternative topology in which it diverges immediately before the animal-fungal dichotomy was recovered. Mitochondrial cristae of Dermocystidium spp. are flat, whereas those of Ichthyophonus hoferi appear tubulovesiculate. These results extend our understanding of the types of organisms from which metazoa and fungi may have evolved.
Methods for Cultivation of Luminal Parasitic Protists of Clinical Importance
Clinical Microbiology Reviews, 2002
SUMMARY Cultivation of luminal protistan parasites has a long history. In this review we discuss the methods and media that are most widely used for the establishment and maintenance of the following organisms in culture: Entamoeba histolytica , Giardia intestinalis , Trichomonas vaginalis , Dientamoeba fragilis , Blastocystis hominis , and Balantidium coli . While cultivation is of limited importance in the diagnostic laboratory, it is essential to most research laboratories, and it is toward the latter that this review is primarily aimed.
Protist (Ciliates) and Related Diseases
2019
Ciliates are one of the most common protistan parasites in cephalopods. In this chapter, we have undertaken to describe the biology and diversity of parasitic ciliates in European cephalopods and give diagnosis elements to identify the known species. We briefly summarize available data on the ciliates parasitizing the gills and skin of European cephalodops (Ancistrocomidae) and the endoparasitic forms observed in the digestive tract and renal appendages (Opalinopsidae). Ancistrocomidae ectoparasites have been observed in Octopus vulgaris. Opalinosidae family harbours two parasitic genera: Opalinopsis and Chromidina. Species diversity of these two genera seems to be underestimated in Europe.
Protist (Coccidia) and Related Diseases
2019
Coccidia of the genus Aggregata is the most widely distributed coccidian in cephalopods. Damages caused to the hosts include mechanical (tissue injury), biochemical (malfunction of digestive enzymes), and molecular (affects cellular immune response) effects. However, coccidiosis is not a fatal disease to the cephalopod host; it severely weakens its innate immunity making it vulnerable to secondary infections. Therefore, coccidia of the genus Aggregata are considered the most dangerous parasite for cephalopods affecting wild species of notable economic importance for fishery and aquaculture activity. The pathology caused by coccidiosis to the most important European cephalopod species is the subject of the present chapter.