Abstract:A double clone of Trypanosoma platydactyli Catouillard, 1909, derived from a single trypomastigote from the blood of the Moorish gecko, Tarentola mauritanica, was grown in vitro. Morphogenesis of the parasites led to a stable population of promastigotes which were identical, in general morphology, ultrastructure and the electrophoretic mobility of 8 enzymes, to those cultures previously considered to be Leishmania tarentolae Wenyon, 1921. These cultures included the strain isolated from the type locality in Al… Show more
“…The use of the lizard leishmania species, L. tarentolae, as a type specimen for the digenetic genus Leishmania is justified by the results of Gomez-Eichelmann et al (18), which showed that lizard leishmania species (including several strains ofL. tarentolae) are indeed more closely related to mammalian leishmania species by several criteria (kinetoplast DNA sequences, nuclear chromosomes, and membrane lipids) than to Trypanosoma species, as has been suggested by Wallbanks et al (19).…”
A phylogenetic tree for the evolution of five representative species from four genera of kinetoplastid protozoa was constructed from comparison of the mitochondrial 9S and 12S rRNA gene sequences and application of both parsmony and evolutionary parsimony algorithms. In the rooted version of the tree, the monogenetic species Crithidia fasciciata is the most deeply rooted, followed by another monogenetic species, Leptomonas sp. The three digenetic speces Trypanosoma cruzi, Trypanosoma brucei, and Leishmania tareDtolae branch from the Leptomonas line. The substitution rates for the T. brucei and T. cruzi sequences were 3-4 times greater than that of the L. tarentolae sequences. This phyloeuettic tree is consistent with our dadistic analysis of the bical evidence including life cycles for these five species. A tentative time scale can be assigned to the nodes of this tree by assnmlng that the common ancestor of the digenetic parasites predated the separation of South America and Africa and postdated the first fossil appearance of its host (inferred by parsimony analysis). This time scale predicts that the deepest node occurred at 264 ± 51 million years ago, at a time commensurate with the fossil origins of the Hemiptera insect host. This implies that the ancestral kinetoplastid and its insect host appeared at approximately the same time. The molecular data suggest that these eukhrybtic parasites have an evolutionary history thkt extends back to the origin of their insect host.The kinetoplastids comprise a widely distributed group of parasitic protozoa that are distinguished by the possession of a single mitochondrion containing a network of catenated mitochondrial DNA minicircles and maxicircles (kinetoplast DNA) in the mitochondrial matrix adjacent to the basal body of the flagellum (1, 2). Two forms of host-protozoan relationships are known: (i) mtonogenetic kinetoplastids that are parasitic in a single invertebrate host and (ii) digenetic kinetoplastids that are parasitic in two hosts, usually an invertebrate and a vertebrate. These lower eukaryotic cells are the subject of both biological and medical interest. The 123 monogenetic species that have been described so far belong to the genera Crithidia, Herpetomonas, Blastocrithidia, and Leptomonas (3). They are parasitic in arthropods (mainly in Insecta, Diptera, and Hemiptera and also in Hymenoptera, Lepidoptera, Orthoptera, and Siphonaptera). The monogenetic species are known as the "lower trypanosomatids" because the digenetic genera Leishmania and Trypanosoma are thought to have arisen from a monogenetic ancestor (4). The morphology of the insect-inhabiting stages of the pathogenic digenetic species resembles that of the monogenetic species.In the absence of a fossil record, a phylogenetic tree must be constructed entirely from biological or, better yet, from molecular sequence data. The mitochondrial 9S and 12S ribosomal RNAs (5-9) represent one such group of conserved sequences that lends itself to analysis. The sequences of both large and small ...
“…The use of the lizard leishmania species, L. tarentolae, as a type specimen for the digenetic genus Leishmania is justified by the results of Gomez-Eichelmann et al (18), which showed that lizard leishmania species (including several strains ofL. tarentolae) are indeed more closely related to mammalian leishmania species by several criteria (kinetoplast DNA sequences, nuclear chromosomes, and membrane lipids) than to Trypanosoma species, as has been suggested by Wallbanks et al (19).…”
A phylogenetic tree for the evolution of five representative species from four genera of kinetoplastid protozoa was constructed from comparison of the mitochondrial 9S and 12S rRNA gene sequences and application of both parsmony and evolutionary parsimony algorithms. In the rooted version of the tree, the monogenetic species Crithidia fasciciata is the most deeply rooted, followed by another monogenetic species, Leptomonas sp. The three digenetic speces Trypanosoma cruzi, Trypanosoma brucei, and Leishmania tareDtolae branch from the Leptomonas line. The substitution rates for the T. brucei and T. cruzi sequences were 3-4 times greater than that of the L. tarentolae sequences. This phyloeuettic tree is consistent with our dadistic analysis of the bical evidence including life cycles for these five species. A tentative time scale can be assigned to the nodes of this tree by assnmlng that the common ancestor of the digenetic parasites predated the separation of South America and Africa and postdated the first fossil appearance of its host (inferred by parsimony analysis). This time scale predicts that the deepest node occurred at 264 ± 51 million years ago, at a time commensurate with the fossil origins of the Hemiptera insect host. This implies that the ancestral kinetoplastid and its insect host appeared at approximately the same time. The molecular data suggest that these eukhrybtic parasites have an evolutionary history thkt extends back to the origin of their insect host.The kinetoplastids comprise a widely distributed group of parasitic protozoa that are distinguished by the possession of a single mitochondrion containing a network of catenated mitochondrial DNA minicircles and maxicircles (kinetoplast DNA) in the mitochondrial matrix adjacent to the basal body of the flagellum (1, 2). Two forms of host-protozoan relationships are known: (i) mtonogenetic kinetoplastids that are parasitic in a single invertebrate host and (ii) digenetic kinetoplastids that are parasitic in two hosts, usually an invertebrate and a vertebrate. These lower eukaryotic cells are the subject of both biological and medical interest. The 123 monogenetic species that have been described so far belong to the genera Crithidia, Herpetomonas, Blastocrithidia, and Leptomonas (3). They are parasitic in arthropods (mainly in Insecta, Diptera, and Hemiptera and also in Hymenoptera, Lepidoptera, Orthoptera, and Siphonaptera). The monogenetic species are known as the "lower trypanosomatids" because the digenetic genera Leishmania and Trypanosoma are thought to have arisen from a monogenetic ancestor (4). The morphology of the insect-inhabiting stages of the pathogenic digenetic species resembles that of the monogenetic species.In the absence of a fossil record, a phylogenetic tree must be constructed entirely from biological or, better yet, from molecular sequence data. The mitochondrial 9S and 12S ribosomal RNAs (5-9) represent one such group of conserved sequences that lends itself to analysis. The sequences of both large and small ...
“…Recently, it has been shown that parasites identified as Trypanosoma platydactylii were identical by isoenzyme profiles to existing laboratory stocks of L. tarentolae (43). The nomenclature and identity of these strains have been called into question (19a, 43), and in this report we refer to these species as L. tarentolae.…”
We describe the structure of amplified DNA that was discovered in two laboratory stocks of the protozoan parasite Leishmania tarentolae. Restriction mapping and molecular cloning revealed that a region of 42 kilobases was amplified 8-to 30-fold in these lines. Southern blot analyses of digested DNAs or chromosomes separated by pulsed-field electrophoresis showed that the amplified DNA corresponded to the H region, a locus defined originally by its amplification in methotrexate-resistant Leishmania major (S. M. Beverley, J. A. Coderre, D. V. Santi, and R. T. Schimke, Cell 38:431439, 1984). Similarities between the amplified DNA of the two species included (i) extensive cross-hybridization; (ii) approximate conservation of sequence order; (iii) extrachromosomal localization; (iv) an overall inverted, head-to-head configuration as a circular 140-kilobase tetrameric molecule; (v) two regions of DNA sequence rearrangement, each of which was closely associated with the two centers of the inverted repeats; (vi) association with methotrexate resistance; and (vii) phenotypically conservative amplification, in which the wild-type chromosomal arrangement was retained without apparent modification. Our data showed that amplified DNA mediating drug resistance arose in unselected L. tarentolae, although the pressures leading to apparently spontaneous amplification and maintenance of the H region are not known. The simple structure and limited extent of DNA amplified in these and other Leishmania lines suggests that the study of gene amplification in Leishmania spp. offers an attractive model system for the study of amplification in cultured mammalian cells and tumors. We also introduced a method for measuring the size of large circular DNAs, using gamma-irradiation to introduce limited double-strand breaks followed by sizing of the linear DNAs by pulsed-field electrophoresis.
“…Box 1. Commercial eukaryotic protein expression systemsThe protozoan Leishmania tarentolae , which was isolated from the Moorish gecko Tarentola mauritanica [82], has been developed into a eukaryotic protein expression system (LEXSY, Jena Bioscience). Its eukaryotic gene expression machinery, which includes full glycosylation and disulfide bond formation, represents a potential advantage over other expression systems.…”
Although the past decade has witnessed the sequencing from an increasing number of parasites, modern high-throughput DNA sequencing technologies have the potential to generate complete genome sequences at even higher rates. Along with the discovery of genes that might constitute potential targets for chemotherapy or vaccination, the need for novel protein expression platforms has become a pressing matter. In addition to reviewing the advantages and limitations of the currently available and emerging expression systems, we discuss novel approaches that could overcome the current limitations, including the 'pseudoparasite' concept, an expression platform in which the choice of the surrogate organism is based on its phylogenetic affinity to the target parasite, while taking advantage of the whole engineered organism as a vaccination adjuvant.
Proteins from protozoan parasites as targets for diagnosis and interventionThe availability of the genome sequences of several parasites of medical importance has led to exponential progress in our understanding of their biology, and enabled the identification of potential targets for intervention [1]. Further, the continued advances in genome sequencing technologies holds great promise for the accomplishment of similar goals for virtually any parasite of interest [2]. When compared to other pathogens of human and veterinary importance, such as viruses and bacteria, large gaps exist in our knowledge of the virulence and pathogenesis mechanisms of protozoan parasites, and methodologies for eradication or management of parasitic diseases through vaccination or treatment are still in the distant future. Characterization of genes of interest for potential intervention identified by mining these genomes has been hindered because of the lack of suitable protein expression systems. A clear example is Plasmodium falciparum, the etiological agent of malaria, for which the lack of an effective vaccine, and the rapid emergence of drug-resistant strains, have made most intervention attempts extremely challenging [3]. Therefore, the development of innovative and efficient systems for the expression of recombinant proteins from protozoan parasites has become an urgent public health matter.
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