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Yarlett N, Jarroll EL, Morada M, Lloyd D. Protists: Eukaryotic single-celled organisms and the functioning of their organelles. Adv Microb Physiol 2024; 84:243-307. [PMID: 38821633 DOI: 10.1016/bs.ampbs.2024.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2024]
Abstract
Organelles are membrane bound structures that compartmentalize biochemical and molecular functions. With improved molecular, biochemical and microscopy tools the diversity and function of protistan organelles has increased in recent years, providing a complex panoply of structure/function relationships. This is particularly noticeable with the description of hydrogenosomes, and the diverse array of structures that followed, having hybrid hydrogenosome/mitochondria attributes. These diverse organelles have lost the major, at one time, definitive components of the mitochondrion (tricarboxylic cycle enzymes and cytochromes), however they all contain the machinery for the assembly of Fe-S clusters, which is the single unifying feature they share. The plasticity of organelles, like the mitochondrion, is therefore evident from its ability to lose its identity as an aerobic energy generating powerhouse while retaining key ancestral functions common to both aerobes and anaerobes. It is interesting to note that the apicoplast, a non-photosynthetic plastid that is present in all apicomplexan protozoa, apart from Cryptosporidium and possibly the gregarines, is also the site of Fe-S cluster assembly proteins. It turns out that in Cryptosporidium proteins involved in Fe-S cluster biosynthesis are localized in the mitochondrial remnant organelle termed the mitosome. Hence, different organisms have solved the same problem of packaging a life-requiring set of reactions in different ways, using different ancestral organelles, discarding what is not needed and keeping what is essential. Don't judge an organelle by its cover, more by the things it does, and always be prepared for surprises.
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Affiliation(s)
- Nigel Yarlett
- Haskins Laboratories, Pace University, New York, NY, United States; The Department of Chemistry and Physical Sciences, Pace University, New York, NY, United States.
| | - Edward L Jarroll
- Department of Biological Sciences, CUNY-Lehman College, Bronx, NY, United States
| | - Mary Morada
- Haskins Laboratories, Pace University, New York, NY, United States
| | - David Lloyd
- Schools of Biosciences and Engineering, Cardiff University, Wales, United Kingdom
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2
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Rigo GV, Trein MR, da Silva Trentin D, Macedo AJ, de Oliveira BA, de Almeida AM, Giordani RB, de Almeida MV, Tasca T. Diamine derivative anti-Trichomonas vaginalis and anti-Tritrichomonas foetus activities by effect on polyamine metabolism. Biomed Pharmacother 2017; 95:847-855. [PMID: 28903180 DOI: 10.1016/j.biopha.2017.09.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 08/21/2017] [Accepted: 09/03/2017] [Indexed: 11/26/2022] Open
Abstract
Human and bovine trichomoniasis are sexually transmitted diseases (STD) caused by Trichomonas vaginalis and Tritrichomonas foetus, respectively. Human trichomoniasis is the most common non-viral STD in the world and bovine trichomoniasis causes significant economic losses to breeders. Considering the significant impact of the infections caused by these protozoa and the treatment failures, the search for new therapeutic alternatives becomes crucial. In this study the effect of diamines and amino alcohols in the in vitro viability of trichomonads was evaluated. Screening demonstrated the high activity of diamine 4 against these protozoa. Although cytotoxicity against HMVII cell line and slight hemolysis were observed in vitro, the compound showed no toxic effect on the Galleria mellonella in vivo model. Importantly, diamine 4 was active against both trichomonads species at 6h and 24h of incubation, and these effects was reverted by putrescine, a polyamine, suggesting competition for the same metabolic pathway. These findings indicate that the mechanism of action of diamine 4 is through the polyamine metabolism, a pathway distinct from that presented by metronidazole, the drug usually used to treat trichomoniasis and to which resistance is widely reported. These data demonstrate the importance of diamines as potential novel candidates as anti-T. vaginalis and anti-T. foetus agents.
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Affiliation(s)
- Graziela Vargas Rigo
- Laboratório de Pesquisa em Parasitologia, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Av. Ipiranga 2752, 90610-000, Porto Alegre, RS, Brazil
| | - Márcia Rodrigues Trein
- Laboratório de Pesquisa em Parasitologia, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Av. Ipiranga 2752, 90610-000, Porto Alegre, RS, Brazil
| | - Danielle da Silva Trentin
- Faculdade de Farmácia e Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre/RS, 90610-000, Brazil; Departamento de Ciências Básicas da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre/RS, 90050-170, Brazil
| | - Alexandre José Macedo
- Faculdade de Farmácia e Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre/RS, 90610-000, Brazil
| | - Bruno Assis de Oliveira
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, Cidade Universitária, Campos Martelos, 36036-900 Juiz de Fora, MG, Brazil
| | - Angelina Maria de Almeida
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, Cidade Universitária, Campos Martelos, 36036-900 Juiz de Fora, MG, Brazil
| | - Raquel Brandt Giordani
- Departamento de Farmácia, Universidade Federal do Rio Grande do Norte, Gustavo Cordeiro de Faria, SN, 59010-180, Natal-RN, Brazil
| | - Mauro Vieira de Almeida
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, Cidade Universitária, Campos Martelos, 36036-900 Juiz de Fora, MG, Brazil
| | - Tiana Tasca
- Laboratório de Pesquisa em Parasitologia, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Av. Ipiranga 2752, 90610-000, Porto Alegre, RS, Brazil.
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3
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Silva NSD, Machado SM, Filho FCES, Pacheco-Soares C. Basic biological aspects of Tritrichomonas foetus of re-levance to the treatment of bovines suffering of tricho-moniasis. ACTA ACUST UNITED AC 2011. [DOI: 10.4236/ojas.2011.13015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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4
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Effects of a putrescine analog on Giardia lamblia. Parasitol Res 2008; 103:363-70. [DOI: 10.1007/s00436-008-0981-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Accepted: 03/31/2008] [Indexed: 10/22/2022]
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5
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Kleydman Y, Yarlett N, Gorrell TE. Production of ammonia by Tritrichomonas foetus and Trichomonas vaginalis. MICROBIOLOGY-SGM 2004; 150:1139-1145. [PMID: 15133073 DOI: 10.1099/mic.0.26939-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Production of ammonia is difficult to find among the various studies of amino acid metabolism in protozoa. Several studies suggest that catabolism of arginine to ammonium is important for the growth of trichomonads. Trichomonads are amitochondriate zooflagellates that thrive under microaerophilic and anaerobic conditions. The authors were able to detect accumulation of ammonium ions and ammonia in cultures of Tritrichomonas foetus and Trichomonas vaginalis, including those resistant to metronidazole. Ammonium ions and ammonia were detected using the indophenol colorimetric method. Cells incubated overnight under an ambient oxygen gas phase had 0.9 mM soluble ammonium (NH(4)(+) and NH(3)) or a 20 % greater concentration of ammonium relative to sterile growth medium that had been incubated similarly. Production of ammonia itself was confirmed by analysis of a wick that was moistened with sulfuric acid (20 mM) and placed above the liquid in sealed cultures of a strain of Trichomonas vaginalis. The wicks from these cultures captured the equivalent of 0.048 mM volatile ammonia (NH(3)) from the liquid as compared to 0.021 mM volatile ammonia from sterile medium after overnight incubation. Intact trichomonads, 0.7 x 10(6) cells ml(-1) equivalent to 0.7 mg protein ml(-1), incubated in Doran's buffer with or without (1 mM) L-arginine produced significant amounts of soluble ammonium (0.07 mM and 0.04 mM, respectively) during 60 min. The results indicate that ammonium ions and the more irritating ammonia are significant metabolites of trichomonads. In addition, based upon end-product amounts, it appears that the rate of arginine metabolism is of the same order of magnitude as that for carbohydrate metabolism by trichomonads.
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Affiliation(s)
| | - Nigel Yarlett
- Department of Chemistry and Physical Sciences, Pace University, New York, NY 10038, USA
- Haskins Laboratories, Pace University, New York, NY 10038, USA
| | - Thomas E Gorrell
- Department of Biology, Pace University, New York, NY 10038, USA
- Haskins Laboratories, Pace University, New York, NY 10038, USA
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6
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Yarlett N, Martinez MP, Goldberg B, Kramer DL, Porter CW. Dependence of Trichomonas vaginalis upon polyamine backconversion. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 10):2715-2722. [PMID: 11021947 DOI: 10.1099/00221287-146-10-2715] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Trichomonas vaginalis grown for 16 h in the presence of [(14)C]spermine formed a high intracellular pool of [(14)C]spermidine and a small but detectable pool of [(14)C]putrescine. When [(3)H]putrescine was added to the growth medium, a large intracellular pool of [(3)H]putrescine was found, but it was not further metabolized, confirming previous studies suggesting the absence of a forward-directed polyamine synthetic pathway in T. vaginalis. Spermidine:spermineN:(1)-acetyltransferase (SSAT) and polyamine oxidase enzyme activities were detected which collectively converted spermine to spermidine. Polyamine oxidase was localized in the hydrogenosome-enriched fraction, whereas SSAT was found predominantly in the cytosolic fraction. In the presence of saturating substrate, the trichomonad SSAT had an activity of 0. 39+/-0.09 nmol min(-1) (mg protein)(-1) (the mean of five analyses) and an apparent K:(m) for spermine of 1.7 microM. The enzyme was competitively inhibited by di(ethyl)norspermine with a K:(i) of 28 microM. Growth studies indicated that 50 microM di(ethyl)norspermine caused a 68% and 84% reduction in the intracellular concentrations of spermidine and spermine, respectively. The trichomonad polyamine oxidase required FAD as a cofactor and had an apparent K:(m) of 6.0 microM for N(1)-acetylspermine. The potential of bis(alkyl) polyamine analogues as antitrichomonad agents is discussed.
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Affiliation(s)
- Nigel Yarlett
- Haskins Laboratories1 and Department of Chemistry and Physical Sciences2, Pace University, 41 Park Row, New York, NY 10038, USA
| | - Martha P Martinez
- Haskins Laboratories1 and Department of Chemistry and Physical Sciences2, Pace University, 41 Park Row, New York, NY 10038, USA
| | - Burt Goldberg
- Department of Biology, St Francis College, 180 Remsen Street, Brooklyn, NY 11201, USA3
- Haskins Laboratories1 and Department of Chemistry and Physical Sciences2, Pace University, 41 Park Row, New York, NY 10038, USA
| | - Debora L Kramer
- Grace Cancer Drug Center, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA4
| | - Carl W Porter
- Grace Cancer Drug Center, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA4
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7
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Reis IA, Martinez MP, Yarlett N, Johnson PJ, Silva-Filho FC, Vannier-Santos MA. Inhibition of polyamine synthesis arrests trichomonad growth and induces destruction of hydrogenosomes. Antimicrob Agents Chemother 1999; 43:1919-23. [PMID: 10428913 PMCID: PMC89391 DOI: 10.1128/aac.43.8.1919] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Trichomonad parasites such as Tritrichomonas foetus produce large amounts of putrescine (1,4-diaminobutane), which is transported out of the cell via an antiport mechanism which results in the uptake of a molecule of spermine. The importance of putrescine to the survival of the parasite and its role in the biology of T. foetus was investigated by use of the putrescine analogue 1, 4-diamino-2-butanone (DAB). Growth of T. foetus in vitro was significantly inhibited by 20 mM DAB, which was reversed by the addition of exogenous 40 mM putrescine. High-performance liquid chromatography analysis of 20 mM DAB-treated T. foetus revealed that putrescine, spermidine, and spermine levels were reduced by 89, 52, and 43%, respectively, compared to those in control cells. The DAB treatment induced several ultrastructural alterations, which were primarily observed in the redox organelles termed hydrogenosomes. These organelles were progressively degraded, giving rise to large vesicles that displayed material immunoreactive with an antibody to beta-succinyl-coenzyme A synthetase, a hydrogenosomal enzyme. A protective role for polyamines as stabilizing agents in the trichomonad hydrogenosomal membrane is proposed.
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Affiliation(s)
- I A Reis
- Laboratório de Biologia da Superfície Celular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil
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8
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Minotto L, Ko GA, Edwards MR, Bagnara AS. Trichomonas vaginalis: expression and characterisation of recombinant S-adenosylhomocysteinase. Exp Parasitol 1998; 90:175-80. [PMID: 9769247 DOI: 10.1006/expr.1998.4319] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The gene encoding S-adenosylhomocysteinase activity (S-adenosylhomocysteine hydrolase, SAHH; EC 3.3.1.1) in Trichomonas vaginalis has been expressed in Escherichia coli to facilitate the characterisation of the enzyme. Expression of this gene using the pQE-30 (6xHis N-terminal tag) expression system (QIAGEN) has enabled the one-step purification of 6 mg of active recombinant enzyme from a 100-ml bacterial culture by affinity chromatography using a nickel-NTA matrix. The recombinant enzyme has a molecular weight of approximately 56,000 and identification of tryptic peptides by matrix-assisted laser desorption ionisation (MALDI) mass spectrometry has shown that the purified recombinant protein is identical in primary structure to the predicted sequence. The presence of the N-terminal 6xHis tag in the recombinant enzyme did not appear to affect its kinetic and other properties, which are similar to those exhibited by the "native" enzyme present in cell-free extracts of T. vaginalis. These properties include a similar apparent Km for adenosine (20-25 microM for the recombinant and 5-10 microM for the native enzymes, respectively) and similar inhibition/inactivation patterns exhibited by adenosine analogues such as arabinosyl adenine (ara-A).
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Affiliation(s)
- L Minotto
- School of Biochemistry and Molecular Genetics, University of New South Wales, Sydney, 2052, Australia
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9
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Schenkel E, Dubois JG, Helson-Cambier M, Hanocq M. Cytotoxicity of polyamines to Amoeba proteus: role of polyamine oxidase. Cell Biol Toxicol 1996; 12:1-9. [PMID: 8882384 DOI: 10.1007/bf00143389] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
It has been shown that oxidation of polyamines by polyamine oxidases can produce toxic compounds (H2O2, aldehydes, ammonia) and that the polyamine oxidase-polyamine system is implicated, in vitro, in the death of several parasites. Using Amoeba proteus as an in vitro model, we studied the cytotoxicity to these cells of spermine, spermidine, their acetyl derivatives, and their hypothetical precursors. Spermine and N1-acetylspermine were more toxic than emetine, an amoebicidal reference drug. Spermine presented a short-term toxicity, but a 48-h contact time was necessary for the high toxicity of spermidine. The uptake by Amoeba cells of the different polyamines tested was demonstrated. On the other hand, a high polyamine oxidase activity was identified in Amoeba proteus crude extract. Spermine (theoretical 100%) and N1-acetylspermine (64%) were the best substrates at pH 9.5, while spermidine, its acetyl derivatives, and putrescine were very poorly oxidized by this enzyme (3-20%). Spermine oxidase activity was inhibited by phenylhydrazine (nil) and isoniazid (approximately 50%). Mepacrine did not inhibit the enzyme activity at pH 8. Neither monoamine nor diamine oxidase activity (approximately 10%) was found. It must be emphasized that spermine, the best enzyme substrate, is the most toxic polyamine. This finding suggests that knowledge of polyamine oxidase specificity can be used to modulate the cytotoxicity of polyamine derivatives. Amoeba proteus was revealed as a simple model for investigation of the connection between cytotoxicity and enzyme activity.
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Affiliation(s)
- E Schenkel
- Laboratory of Toxicology and Bioanalytical Chemistry, Université Libre de Bruxelles (ULB), Belgium
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10
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Reguera RM, Fouce RB, Cubría JC, Bujidos ML, Ordóñez D. Fluorinated analogues of L-ornithine are powerful inhibitors of ornithine decarboxylase and cell growth of Leishmania infantum promastigotes. Life Sci 1994; 56:223-30. [PMID: 7823781 DOI: 10.1016/0024-3205(94)00916-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Fluorinated analogues of L-ornithine have been tested on growth and ornithine decarboxylase arising from L.infantum cytosolic extracts. EC50 values estimated from dose/response curves were 38 microM, 2.62 microM and 4.64 microM for alpha-DFMO, delta-MFMO and delta-MFMOme respectively. Also the inhibition produced by all three compounds was effectively reverted by exogenous putrescine, pointing towards the inhibition of L.infantum ODC. ODC from logarithmic phase cytosolic extracts was physicochemically and kinetically characterized, showing a long half-life (more than 24 h) and a km value for L-ornithine of 98 microM. Finally, the inhibitory effect of fluorinated analogues of L-ornithine was analysed on L.infantum ODC showing a time-dependent irreversible behavior, with Ki values estimated on 125 microM, T1/2 3.5 min for alpha-DFMO; 13.3 microM, T1/2 1.8 min for delta-MFMO and 4.3 microM, T1/2 4 min for delta-MFMOme.
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Affiliation(s)
- R M Reguera
- Departamento de Fisiología, Farmacología y Toxicología, Facultad de Veterinaria, Universidad de León, Spain
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11
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Yarlett N, Goldberg B, Moharrami MA, Bacchi CJ. Trichomonas vaginalis: characterization of ornithine decarboxylase. Biochem J 1993; 293 ( Pt 2):487-93. [PMID: 8343128 PMCID: PMC1134387 DOI: 10.1042/bj2930487] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Ornithine decarboxylase (ODC), the lead enzyme in polyamine biosynthesis, was partially purified from Trichomonas vaginalis and its kinetic properties were studied. The enzyme appears to be of special significance in this anaerobic parasite, since the arginine dihydrolase pathway generates ATP as well as putrescine from arginine. ODC from T. vaginalis had a broad substrate specificity, decarboxylating ornithine (100%), lysine (1.0%) and arginine (0.1%). The enzyme had a pH optimum of 6.5, a temperature optimum of 37 degrees C and was pyridoxal 5'-phosphate-dependent. Attempts to separate ornithine- from lysine-decarboxylating activity by thermal-stability and pH-optima curves were not successful. Although Km values for ornithine and lysine were 109 and 91 microM respectively, and the Vmax values for these substrates were 1282 and 13 nmol/min per mg of protein respectively, the most important intracellular substrate is ornithine, since intracellular ornithine levels are 3.5 times those of lysine and extracellular putrescine levels are 7.5 times those of cadaverine. Ornithine was also an effective inhibitor of lysine-decarboxylating activity (Ki 150 microM), whereas lysine was relatively ineffective as inhibitor of ornithine-decarboxylating activity (Ki 14.5 mM). Crude ODC activity was localized (86%) in the 43,000 g supernatant and 3303-fold purification was obtained by (NH4)2SO4 salting and DEAE-Sephacel, agarose-gel and hydroxyapatite chromatography steps. The enzyme bound difluoro[3H]methylornithine ([3H]DFMO) with a ratio of drug bound to activity of 2500 fmol/unit, where 1 unit corresponds to 1 nmol of CO2 released from ornithine/min. The enzyme had a native M(r) of 210000 (gel filtration), with a subunit M(r) of 55,000 (by SDS/PAGE), suggesting that the trichomonad enzyme is a tetramer. From the subunit M(r) and binding ratio of DFMO, there is about 137 ng of ODC per mg of T. vaginalis protein (0.013%). The significant amount of ODC protein present supports the view that putrescine synthesis in T. vaginalis plays an important role in the metabolism of the parasite.
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Affiliation(s)
- N Yarlett
- Haskins Laboratories, Pace University, New York, NY 10038
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12
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Williams AG, Lloyd D. Biological Activities of Symbiotic and Parasitic Protozoa and Fungi in Low-Oxygen Environments. ADVANCES IN MICROBIAL ECOLOGY 1993. [DOI: 10.1007/978-1-4615-2858-6_5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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13
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Wright CW, Phillipson JD. Natural products and the development of selective antiprotozoal drugs. Phytother Res 1990. [DOI: 10.1002/ptr.2650040402] [Citation(s) in RCA: 130] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Schofield PJ, Costello M, Edwards MR, O'Sullivan WJ. The arginine dihydrolase pathway is present in Giardia intestinalis. Int J Parasitol 1990; 20:697-9. [PMID: 2228433 DOI: 10.1016/0020-7519(90)90133-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Growth of Giardia intestinalis in Diamond's TYI-S-33 medium is characterized by a rapid depletion of the arginine in the medium, and concurrent production of ornithine and ammonia. [Guanidino-14C] arginine was converted to 14CO2 by extracts of G. intestinalis suggesting the presence of the arginine dihydrolase pathway. This was confirmed by the detection of arginine deiminase, catabolic ornithine transcarbamylase, carbamate kinase and ornithine decarboxylase in giardial extracts. The findings demonstrate for the first time the existence of the arginine dihydrolase pathway in Giardia, and suggest that arginine metabolism via this pathway plays a significant role in energy metabolism by providing a site for anaerobic substrate level phosphorylation.
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Affiliation(s)
- P J Schofield
- School of Biochemistry, University of NSW, Kensington, Australia
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15
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Lehker MW, Alderete JF. Properties of Trichomonas vaginalis grown under chemostat controlled growth conditions. Genitourin Med 1990; 66:193-9. [PMID: 2370063 PMCID: PMC1194501 DOI: 10.1136/sti.66.3.193] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Trichomonas vaginalis isolates NYH 286 and IR 78 were grown in continuous flow culture conditions in a complex trypticase-yeast extract-maltose medium supplemented with heat-inactivated horse serum. Parasites could be stably maintained in the chemostat at high densities ranging from 1 x 10(6) to 1 x 10(7) organisms ml-1. Growth densities, acid production, and profiles of total versus secreted trichomonad proteins were characterised at different rates of growth and pH. Growth rate influenced the extent of parasite production of acid and the shedding of proteins into the medium but had no effect on overall parasite density. Lowering the pH from 6.0 to 5.0 resulted both in a decrease of cell density and acid production. At pH 4.5 isolate IR 78 but not NYH 286 was capable of growth and multiplication, showing the ability of some isolates to survive at the vaginal pH of healthy individuals. At this lower pH, however, isolate NYH 286 but not IR 78 synthesised new proteins which were detectable in stained gels. Also, inoculation of the chemostat with isolate NYH 286 comprising a mixture of fluorescent (positive, pos) and non-fluorescent (negative, neg) trichomonads as defined by monoclonal antibody reactivity to a surface immunogen resulted in a change in the parasite population to an almost homogeneous neg phenotype. These neg phenotype organisms switched back to pos phenotype after transfer to test tubes.
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Affiliation(s)
- M W Lehker
- Department of Microbiology, University of Texas Health Science Center, San Antonio
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