Lysosomal enzymes in extracellular digestion in the unicellular eukaryote <i>Tetrahymena</i>

Tiedtke, Arno; Rasmussen, Leif

doi:10.1002/jcp.1041360324

Cited by 15 publications

(15 citation statements)

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“…In these studies, proteases were suggested to be involved in both intracellular and extracellular digestion. In addition, lysosomal-released enzymes from T. thermophilia have been implicated in the process of extracellular digestion and parasite nutrition, with proteolytic enzymes facilitating the release of host particulate and soluble nutrients (Florin-Christensen et al 1985, Tiedtke & Rasmussen 1988. Thus, the proteases released by the present ciliate under investigation may also play a similar role in nutrient uptake, both in vitro and in vivo.…”

Section: Discussionmentioning

confidence: 99%

Identification and partial characterisation of metalloproteases secreted by a Mesanophrys-like ciliate parasite of the Norway lobster Nephrops norvegicus

Small¹,

Neil²,

Taylor³

et al. 2005

Dis. Aquat. Org.

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A ciliate parasite, tentatively identified as Mesanophrys sp. of Norway lobstersNephrops norvegicus, is demonstrated to secrete several proteases into the culture medium (modified Nephrops saline). Analyses using substrate-impregnated sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed 12 activity bands differing greatly in mobility in the gels. The complete inhibition of proteolytic activity by 1,10-phenanthroline indicated that the proteases are of the metallo class. The proteases were active at the physiological temperature (8°C) and haemolymph pH (7.8) of the host. The proteases were selective in the degradation of several host proteins, including the myosin heavy chain, which is a major structural component of lobster muscle. Consequently, these proteases may have important roles in several aspects of the host -parasite interaction including invasion, nutrient uptake by the ciliate, and pathogenesis.KEY WORDS: Ciliate · Parasite · Proteases · Secreted · Pathology Resale or republication not permitted without written consent of the publisherDis Aquat Org 67: [225][226][227][228][229][230][231] 2005 ( Lee et al. 2003); in this case, secreted proteases may be directly responsible for many of the clinical symptoms associated with the disease, such as tissue necrosis.Several reports of Mesanophrys spp. infections in crustaceans have indicated that these ciliates infiltrate and consume host tissues and haemocytes (Poisson 1930, Bang et al. 1972, Messick & Small 1996. The discovery of a Mesanophrys-like parasitic ciliate infecting Norway lobsters Nephrops norvegicus, and isolation of the ciliate via in vitro cultivation, has allowed proteolytic factors that may play a role in the parasite's establishment and proliferation to be investigated. This paper reports on the characterisation of these proteases, and suggests ways in which they may be involved in the pathogenesis of ciliate disease in lobsters. MATERIALS AND METHODSIsolation and cultivation of the ciliate parasite. Routine screening of Nephros norvegicus from the Clyde Sea area for the parasitic dinoflagellate Hematodinium sp. led to the discovery and identification of a ciliate infection in several Norway lobsters (Small et al. 2005). Haemolymph samples were withdrawn aseptically from the base of the fifth pereiopod using a 1 ml disposable syringe and 25-gauge needle following sterilisation of the cuticle with 70% (v/v) ethanol. Ciliate infections were diagnosed by viewing haemolymph smears using light microscopy. Parasitic ciliates were isolated in 3.5 cm well plates with 0.2 ml infected haemolymph added to 5 ml culture medium in each well. The culture medium comprised 10% (v/v) ) and streptomycin (10 µg ml -1 ) were added to inhibit bacterial contamination. The medium was filter-sterilised (0.2 µm) after the addition of all constituents. Cultures were incubated at 8°C. Serial subculturing gave rise to axenic cultures.Experimental subcultures for protease analyses were initiated with the addition of 1 × 10 5 ciliate...

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Section: Discussionmentioning

confidence: 99%

Identification and partial characterisation of metalloproteases secreted by a Mesanophrys-like ciliate parasite of the Norway lobster Nephrops norvegicus

Small¹,

Neil²,

Taylor³

et al. 2005

Dis. Aquat. Org.

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“…The cells were neither rescued by a number of triglycerides, a I ,3-diglyceride, nor by short-chain alcohols (< C,d. [20] and of growth-controlling compounds [6] from the living cells themselves seems to preclude a strict use of the concept of a synthetic nutrient medium from the moment of inoculation.…”

Section: Resultsmentioning

confidence: 99%

Survival of Tetrahymena thermophila at Low Initial Cell Densities. Effects of Lipids and Long‐Chain Alcohols

Schousboe

Rasmussen

1994

J Eukaryotic Microbiology

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Cells of the ciliate Tetrahymena thermophila failed to establish cultures in lipid-free standard synthetic nutrient medium if the initial population density was 250 cells per ml or less. These cells died within 10 h, but were saved and formed dense cultures if their medium was supplemented with 10 micrograms per ml of either certain phospholipids, 1,2-di-, 1-monoglycerides, fatty acids, long-chain alcohols, or sterols. Cell multiplication was followed in cultures in which the standard synthetic medium was supplemented with a selection of the compounds listed above. It was observed that the cells in the supplemented cultures in their exponential phases of growth had about the same average doubling times as control cells starting multiplication at 10-fold higher initial cell densities in lipid-free medium. These cells have been grown for decades in lipid-free synthetic nutrient media at short (ca. two-three h) doubling times. Therefore lipids have been considered nutritionally non-essential for growth and multiplication of these cells. We propose that those compounds that rescue the cells at low cell densities act as "proliferation signals," sensu lato. This effect of lipids and long-chain alcohols has so far remained unnoticed.

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“…Creative strategies exist (or may need to be developed) to identify a mutant with a phenotype of interest. Notably, swimming assays for cilia defects, fluorescent detection of secreted proteases for exocytosis defects, and density gradients for feeding defects have been successfully employed (Nilsson and van Deurs 1983;Hünseler et al 1987;Pennock et al 1988;Tiedtke and Rasmussen 1988).…”

Section: Forward Genetics: Unbiased Gene Discoverymentioning

confidence: 99%

Tetrahymenaas a Unicellular Model Eukaryote: Genetic and Genomic Tools

2016

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Tetrahymena thermophila is a ciliate model organism whose study has led to important discoveries and insights into both conserved and divergent biological processes. In this review, we describe the tools for the use of Tetrahymena as a model eukaryote, including an overview of its life cycle, orientation to its evolutionary roots, and methodological approaches to forward and reverse genetics. Recent genomic tools have expanded Tetrahymena's utility as a genetic model system. With the unique advantages that Tetrahymena provide, we argue that it will continue to be a model organism of choice.

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Lysosomal enzymes in extracellular digestion in the unicellular eukaryote Tetrahymena

Cited by 15 publications

References 13 publications

Identification and partial characterisation of metalloproteases secreted by a Mesanophrys-like ciliate parasite of the Norway lobster Nephrops norvegicus

Identification and partial characterisation of metalloproteases secreted by a Mesanophrys-like ciliate parasite of the Norway lobster Nephrops norvegicus

Survival of Tetrahymena thermophila at Low Initial Cell Densities. Effects of Lipids and Long‐Chain Alcohols

Tetrahymenaas a Unicellular Model Eukaryote: Genetic and Genomic Tools

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