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Abstract
Plasmalogen synthesis can be analyzed by metabolic labeling, followed by the separation of ethanolamine plasmalogens from glycerophospholipids on one-dimensional thin-layer chromatography. The vinyl-ether bond of plasmalogens is acid-labile, which allows separating plasmalogens as 2-acyl-glycerophospholipids from diacyl-glycerophospholipids.
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Affiliation(s)
- Masanori Honsho
- Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Yukio Fujiki
- Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
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2
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Honsho M, Yagita Y, Kinoshita N, Fujiki Y. Isolation and characterization of mutant animal cell line defective in alkyl-dihydroxyacetonephosphate synthase: Localization and transport of plasmalogens to post-Golgi compartments. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:1857-65. [DOI: 10.1016/j.bbamcr.2008.05.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Revised: 05/02/2008] [Accepted: 05/21/2008] [Indexed: 10/22/2022]
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3
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Zheng H, Duclos RI, Smith CC, Farber HW, Zoeller RA. Synthesis and biological properties of the fluorescent ether lipid precursor 1-O-[9'-(1''-pyrenyl)]nonyl-sn-glycerol. J Lipid Res 2005; 47:633-42. [PMID: 16369049 DOI: 10.1194/jlr.m500493-jlr200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The synthesis of an omega-pyrene-labeled 1-O-alkyl-sn-glycerol was performed using a chirospecific method starting from R-(-)-2,3-O-isopropylidene-sn-glycerol. The product, 1-O-[9'-(1''-pyrenyl)]nonyl-sn-glycerol (pAG), is a fluorescent ether lipid that has a pyrene moiety covalently attached at the alkyl chain terminus. pAG was taken into CHO-K1 cells and a plasmalogen-deficient variant of CHO-K1, NRel-4. This variant is defective in dihydroxyacetonephosphate acyltransferase, which catalyzes the first step in plasmenylethanolamine (PlsEtn) biosynthesis. pAG was incorporated primarily into ethanolamine and choline phospholipids as well as a neutral lipid fraction tentatively identified as alkyldiacylglycerol. NRel-4 accumulated more fluorescence in the phospholipid fraction than CHO-K1, specifically in the ethanolamine phospholipids. Analysis of the fluorescent lipids showed that 93% of the pAG was incorporated into glycerolipids with the ether bond intact. Although the addition of 20 microM 1-O-hexadecyl-sn-glycerol to the medium fully restored PlsEtn biosynthesis in NRel-4 cells, pAG only partially restored PlsEtn synthesis. Incubation of cells with pAG followed by irradiation with long-wavelength (>300 nm) ultraviolet light resulted in cytotoxicity. NRel-4 cells displayed an increased sensitivity to this treatment compared with CHO-K1 cells. This photodynamic cytotoxicity approach could be used to select for mutants that are defective in downstream steps in ether lipid biosynthesis.
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Affiliation(s)
- Hongying Zheng
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118-2526, USA
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4
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Liu D, Nagan N, Just WW, Rodemer C, Thai TP, Zoeller RA. Role of dihydroxyacetonephosphate acyltransferase in the biosynthesis of plasmalogens and nonether glycerolipids. J Lipid Res 2005; 46:727-35. [PMID: 15687349 DOI: 10.1194/jlr.m400364-jlr200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The variant CHO-K1 cell line, NRel-4, is unable to synthesize plasmalogens because of a severe reduction in dihydroxyacetonephosphate acyltransferase (DHAPAT) activity (Nagan, N., A. K. Hajra, L. K. Larkins, P. Lazarow, P. E. Purdue, W. B. Rizzo, and R. A. Zoeller. 1998. Isolation of a Chinese hamster fibroblast variant defective in dihydroxyacetonephosphate acyltransferase activity and plasmalogen biosynthesis: use of a novel two-step selection protocol. Biochem. J. 332: 273-279). Northern analysis demonstrated that the loss of this activity was attributable to a severe reduction in mRNA levels for DHAPAT. Transfection of NRel-4 cells with a plasmid bearing the human DHAPAT cDNA recovered DHAPAT activity and plasmalogen biosynthesis. Examination of clonal isolates from the transfected population showed that recovery of as little as 10% of wild-type DHAPAT activity restored plasmalogen levels to 55% of normal, whereas in one isolate, NRel-4.15, which overexpressed DHAPAT activity by 6-fold over wild-type cells, plasmalogen levels were returned only to wild-type values. Although the rate of plasmenylethanolamine biosynthesis was restored in NRel-4.15, the biosynthesis of nonether glycerolipids was either decreased or unaffected, suggesting that peroxisomal DHAPAT does not normally contribute to nonether glycerolipid biosynthesis. These data demonstrate that a defect in the gene that codes for peroxisomal DHAPAT is the primary lesion in the NRel-4 cell line and that the peroxisomal DHAPAT is essential for the biosynthesis of plasmalogens in animal cells.
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Affiliation(s)
- Dailan Liu
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118, USA
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5
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Munn NJ, Arnio E, Liu D, Zoeller RA, Liscum L. Deficiency in ethanolamine plasmalogen leads to altered cholesterol transport. J Lipid Res 2003; 44:182-92. [PMID: 12518037 DOI: 10.1194/jlr.m200363-jlr200] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmalogens are a major sub-class of ethanolamine and choline phospholipids in which the sn-1 position has a long chain fatty alcohol attached through a vinyl ether bond. These phospholipids are proposed to play a role in membrane fusion-mediated events. In this study, we investigated the role of the ethanolamine plasmalogen plasmenylethanolamine (PlsEtn) in intracellular cholesterol transport in Chinese hamster ovary cell mutants NRel-4 and NZel-1, which have single gene defects in PlsEtn biosynthesis. We found that PlsEtn was essential for specific cholesterol transport pathways, those from the cell surface or endocytic compartments to acyl-CoA/cholesterol acyltransferase in the endoplasmic reticulum. The movement of cholesterol from the endoplasmic reticulum or endocytic compartments to the cell surface was normal in PlsEtn-deficient cells. Also, vesicle trafficking was normal in PlsEtn-deficient cells, as measured by fluid phase endocytosis and exocytosis, as was the movement of newly-synthesized proteins to the cell surface. The mutant cholesterol transport phenotype was due to the lack of PlsEtn, since it was corrected when NRel-4 cells were transfected with a cDNA encoding the missing enzyme or supplied with a metabolic intermediate that enters the PlsEtn biosynthetic pathway downstream of the defect. Future work must determine the precise role that plasmalogens have on cholesterol transport to the endoplasmic reticulum.
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Affiliation(s)
- Natalie J Munn
- Department of Physiology, Tufts University School of Medicine, Boston, MA 02111, USA
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6
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Vance DE. Chapter 8 Phospholipid biosynthesis in eukaryotes. BIOCHEMISTRY OF LIPIDS, LIPOPROTEINS AND MEMBRANES, 4TH EDITION 2002. [DOI: 10.1016/s0167-7306(02)36010-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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7
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Plasmalogens as endogenous antioxidants: somatic cell mutants reveal the importance of the vinyl ether. Biochem J 1999. [PMID: 10051451 DOI: 10.1042/0264-6021:3380769] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Exposure of plasmalogen-deficient variants of the murine cell line RAW 264.7 to short-term (0-100 min) treatment with electron transport inhibitors antimycin A or cyanide (chemical hypoxia) resulted in a more rapid loss of viability than in the parent strain. Results suggested that plasmalogen-deficient cells were more sensitive to reactive oxygen species (ROS) generated during chemical hypoxia; the mutants could be rescued from chemical hypoxia by using the antioxidant Trolox, an alpha-tocopherol analogue, and they were more sensitive to ROS generation by plumbagin or by rose bengal treatment coupled with irradiation. In addition, the use of buffers containing 2H2O greatly enhanced the cytotoxic effect of chemical hypoxia, suggesting the involvement of singlet oxygen. We used the unique enzymic deficiencies displayed by the mutants to differentially restore either plasmenylethanolamine (the major plasmalogen species normally found in this cell line) or its biosynthetic precursor, plasmanylethanolamine. Restoration of plasmenylethanolamine, which contains the vinyl ether, resulted in wild-type-like resistance to chemical hypoxia and ROS generators, whereas increasing levels of its precursor, which bears the saturated ether, had no effect on cell survival. These findings identify the vinyl ether double bond as a crucial element in cellular protection under these conditions and support the hypothesis that plasmalogens, through the vinyl ether, act as antioxidants to protect cells against ROS. These phospholipids might protect cells from ROS-mediated damage during events such as chemical hypoxia.
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8
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Plasmalogens as endogenous antioxidants: somatic cell mutants reveal the importance of the vinyl ether. Biochem J 1999. [PMID: 10051451 DOI: 10.1042/bj3380769] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Exposure of plasmalogen-deficient variants of the murine cell line RAW 264.7 to short-term (0-100 min) treatment with electron transport inhibitors antimycin A or cyanide (chemical hypoxia) resulted in a more rapid loss of viability than in the parent strain. Results suggested that plasmalogen-deficient cells were more sensitive to reactive oxygen species (ROS) generated during chemical hypoxia; the mutants could be rescued from chemical hypoxia by using the antioxidant Trolox, an alpha-tocopherol analogue, and they were more sensitive to ROS generation by plumbagin or by rose bengal treatment coupled with irradiation. In addition, the use of buffers containing 2H2O greatly enhanced the cytotoxic effect of chemical hypoxia, suggesting the involvement of singlet oxygen. We used the unique enzymic deficiencies displayed by the mutants to differentially restore either plasmenylethanolamine (the major plasmalogen species normally found in this cell line) or its biosynthetic precursor, plasmanylethanolamine. Restoration of plasmenylethanolamine, which contains the vinyl ether, resulted in wild-type-like resistance to chemical hypoxia and ROS generators, whereas increasing levels of its precursor, which bears the saturated ether, had no effect on cell survival. These findings identify the vinyl ether double bond as a crucial element in cellular protection under these conditions and support the hypothesis that plasmalogens, through the vinyl ether, act as antioxidants to protect cells against ROS. These phospholipids might protect cells from ROS-mediated damage during events such as chemical hypoxia.
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Delude RL, Yoshimura A, Ingalls RR, Golenbock DT. Construction of a Lipopolysaccharide Reporter Cell Line and Its Use in Identifying Mutants Defective in Endotoxin, But Not TNF-α, Signal Transduction. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.161.6.3001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Gram-negative bacterial LPS is a potent activator of inflammatory responses. The binding of LPS to CD14 initiates signal transduction; however, the molecular processes immediately following this event remain unclear. We engineered an LPS-inducible fibroblast reporter cell line to facilitate the use of molecular genetic techniques to study the LPS signaling pathway. A plasmid containing the human Tac Ag cDNA under transcriptional control of the human E selectin promoter was cotransfected into Chinese hamster ovary (CHO)-K1 cells together with a CD14 expression plasmid. A cell line was obtained, 3E10, which up-regulated expression of Tac following stimulation with LPS. Pools of mutagenized cells were exposed to LPS and then labeled with anti-Tac mAb. Cells that failed to up-regulate Tac expression were enriched by flow cytometry. Thirty clonal mutant cell lines were identified that continued to express CD14 and bind LPS, but failed to express Tac or translocate nuclear factor-κB (NF-κB) following LPS exposure. TNF-α-treated mutant cells continued to express Tac and translocate NF-κB. An analysis of LPS-induced NF-κB activity in heterokaryons derived from polyethylene glycol-fused cell lines indicated that recessive mutations in genes encoding components of the LPS signaling pathway accounted for the signaling defects. To date, two complementation groups have been identified from 11 cell lines analyzed. These data demonstrate that the TNF-α signaling pathway diverges from the LPS pathway early in the signal-transduction cascade despite similarities in LPS- and TNF-α-induced responses. Identification of the genes affected in these mutant reporter cells should identify heretofore-elusive components of the LPS signaling cascade.
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Affiliation(s)
- Russell L. Delude
- *Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215; and
| | - Atsutoshi Yoshimura
- †Maxwell Finland Laboratory for Infectious Diseases, Boston University School of Medicine, Boston Medical Center, Boston, MA 02118
| | - Robin R. Ingalls
- †Maxwell Finland Laboratory for Infectious Diseases, Boston University School of Medicine, Boston Medical Center, Boston, MA 02118
| | - Douglas T. Golenbock
- †Maxwell Finland Laboratory for Infectious Diseases, Boston University School of Medicine, Boston Medical Center, Boston, MA 02118
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Nagan N, Hajra AK, Larkins LK, Lazarow P, Purdue PE, Rizzo WB, Zoeller RA. Isolation of a Chinese hamster fibroblast variant defective in dihydroxyacetonephosphate acyltransferase activity and plasmalogen biosynthesis: use of a novel two-step selection protocol. Biochem J 1998; 332 ( Pt 1):273-9. [PMID: 9576878 PMCID: PMC1219478 DOI: 10.1042/bj3320273] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We have developed a two-step selection protocol to generate a population of Chinese hamster ovary (CHO) cell variants that are plasmalogen-deficient, but contain intact, functional peroxisomes (plasmalogen-/peroxisome+). This involved sequential exposures of a mutagenized cell population to photodynamic damage by using two different pyrene-labelled sensors, 9-(1'-pyrene)nonanol and 12-(1'-pyrene)dodecanoic acid. By this procedure we generated several isolates, all except one of which displayed a severe decrease in plasmalogen biosynthesis. Further characterization of one of the plasmalogen-deficient isolates, NRel-4, showed that it contained intact, functional peroxisomes. Whole-cell homogenates from NRel-4 displayed severely decreased dihydroxyacetone phosphate acyltransferase, which catalyses the first step in plasmalogen biosynthesis. NRel-4 and another, recently described, plasmalogen-deficient cell line, NZel-1 [Nagan, Hajra, Das, Moser, Moser, Lazarow, Purdue and Zoeller (1997) Proc. Natl. Acad. Sci. U.S. A. 94, 4475-4480] were hypersensitive to singlet oxygen, supporting the notion of plasmalogens as radical oxygen scavengers. Wild-type-like resistance could be conferred on NRel-4 upon restoration of plasmalogen content by supplementation with a bypass compound, sn-1-hexadecylglycerol. NRel-4 and other plasmalogen-/peroxisome+ strains will allow us to examine further the role of ether lipids in cellular functions without complications associated with peroxisome deficiency, and might serve as an animal cell model for certain forms of the human genetic disorder rhizomelic chondrodysplasia punctata.
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Affiliation(s)
- N Nagan
- Department of Biophysics, Boston University School of Medicine, 80 East Concord Street, Boston, MA 02118, USA
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11
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Subramani S. Components involved in peroxisome import, biogenesis, proliferation, turnover, and movement. Physiol Rev 1998; 78:171-88. [PMID: 9457172 DOI: 10.1152/physrev.1998.78.1.171] [Citation(s) in RCA: 267] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In the decade that has elapsed since the discovery of the first peroxisomal targeting signal (PTS), considerable information has been obtained regarding the mechanism of protein import into peroxisomes. The PTSs responsible for the import of matrix and membrane proteins to peroxisomes, the receptors for several of these PTSs, and docking proteins for the PTS1 and PTS2 receptors are known. Many peroxins involved in peroxisomal protein import and biogenesis have been characterized genetically and biochemically. These studies have revealed important new insights regarding the mechanism of protein translocation across the peroxisomal membrane, the conservation of PEX genes through evolution, the role of peroxins in fatal human peroxisomal disorders, and the biogenesis of the organelle. It is clear that peroxisomal protein import and biogenesis have many features unique to this organelle alone. More recent studies on peroxisome degradation, division, and movement highlight newer aspects of the biology of this organelle that promise to be just as exciting and interesting as import and biogenesis.
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Affiliation(s)
- S Subramani
- Department of Biology, University of California at San Diego, La Jolla, USA
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12
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Nagan N, Hajra AK, Das AK, Moser HW, Moser A, Lazarow P, Purdue PE, Zoeller RA. A fibroblast cell line defective in alkyl-dihydroxyacetone phosphate synthase: a novel defect in plasmalogen biosynthesis. Proc Natl Acad Sci U S A 1997; 94:4475-80. [PMID: 9114014 PMCID: PMC20747 DOI: 10.1073/pnas.94.9.4475] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Using fluorescence-activated cytotoxicity selection, followed by colony autoradiographic screening of the surviving population, we have isolated a unique plasmalogen-deficient Chinese hamster ovary (CHO) cell line. The mutant, NZel-1, showed a dramatic (90%) reduction in the rate of biosynthesis and levels of plasmalogens, as determined using short- and long-term labeling with 32Pi. Enzymatic assays and lipid supplementation studies showed that NZel-1 was defective in a single step in the biosynthetic pathway for plasmalogens. This step, catalyzed by the peroxisomal enzyme, alkyl-dihydroxyacetone phosphate (DHAP) synthase, is responsible for the introduction of the ether bond found in plasmalogens. The activity of alkyl-DHAP synthase was reduced in whole-cell homogenates from NZel-1 to 18% of wild-type values. Unlike previously described plasmalogen-deficient mutants, NZel-1 contained peroxisomes, as confirmed by immunofluorescence microscopy and catalase release by digitonin. Peroxisomal functions, including the breakdown of very long-chain (>20 carbons) fatty acids, phytanic acid oxidation, and the acylation of DHAP, were normal. Cell fusion studies revealed that the mutation is recessive and belongs to a new complementation group. To our knowledge this is the first report describing the isolation and characterization of a mutant CHO cell line defective in plasmalogen biosynthesis which contains intact, functional peroxisomes. These cells will allow us to examine the role of ether lipids in cellular functions without complications associated with peroxisome deficiency.
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Affiliation(s)
- N Nagan
- Department of Biophysics, Boston University School of Medicine, Boston, MA 02118, USA
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Decreased phosphatidylcholine biosynthesis and abnormal distribution of CTP:phosphocholine cytidylyltransferase in cholesterol auxotrophic Chinese hamster ovary cells. J Lipid Res 1997. [DOI: 10.1016/s0022-2275(20)37238-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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14
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Vance DE. Glycerolipid biosynthesis in eukaryotes. BIOCHEMISTRY OF LIPIDS, LIPOPROTEINS AND MEMBRANES 1996. [DOI: 10.1016/s0167-7306(08)60513-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Carruthers VB, Cross GA. High-efficiency clonal growth of bloodstream- and insect-form Trypanosoma brucei on agarose plates. Proc Natl Acad Sci U S A 1992; 89:8818-21. [PMID: 1528898 PMCID: PMC50012 DOI: 10.1073/pnas.89.18.8818] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
This report describes a method for growing both bloodstream- and procyclic-form Trypanosoma brucei as colonies on agarose plates. Procyclic colonies, which took 2 weeks to develop, grew with approximately 17% plating efficiency on SDM-79/0.65% agarose supplemented with 20% (vol/vol) conditioned medium. Bloodstream forms were adapted to in vitro growth in liquid HMI-9 medium and then spread on HMI-9/0.65% agarose plates, where they grew to visible colonies in 3-5 days. Plating efficiencies were from 3 to 80%, depending upon the trypanosome variant and experiment. Colonies were proven to be the result of growth from a single cell and contained approximately 10(6) cells at maturity. Colonies were transferred to filters and probed for multicopy and single-copy genes. Potential uses of this method in conjunction with classical and reverse genetic approaches to studying trypanosomes are discussed.
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Affiliation(s)
- V B Carruthers
- Laboratory of Molecular Parasitology, Rockefeller University, New York, NY 10021
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