Here we report that trypanosomatid flagellates of the genus Blastocrithidia possess catalase. Thi... more Here we report that trypanosomatid flagellates of the genus Blastocrithidia possess catalase. This enzyme is not phylogenetically related to the previously characterized catalases in other monoxenous trypanosomatids, suggesting that their genes have been acquired independently. Surprisingly, Blastocrithidia catalase is less enzymatically active, compared to its counterpart from Leptomonas pyrrhocoris, posing an intriguing biological question why this gene has been retained in the evolution of trypanosomatids.
Fe-S clusters are ubiquitous cofactors of proteins involved in a variety of essential cellular pr... more Fe-S clusters are ubiquitous cofactors of proteins involved in a variety of essential cellular processes. The biogenesis of Fe-S clusters in the cytosol and their insertion into proteins is accomplished through the cytosolic iron-sulphur protein assembly (CIA) machinery. The early- and middle-acting modules of the CIA pathway concerned with the assembly and trafficking of Fe-S clusters have been previously characterised in the parasitic protist Trypanosoma brucei. In this study, we applied proteomic and genetic approaches to gain insights into the network of protein-protein interactions of the late-acting CIA targeting complex in T. brucei. All components of the canonical CIA machinery are present in T. brucei including, as in humans, two distinct CIA2 homologues TbCIA2A and TbCIA2B. These two proteins are found interacting with TbCIA1, yet the interaction is mutually exclusive, as determined by mass spectrometry. Ablation of most of the components of the CIA targeting complex by RN...
Mitochondria are double membrane organelles of endosymbiotic origin, best known for constituting ... more Mitochondria are double membrane organelles of endosymbiotic origin, best known for constituting the centre of energetics of a eukaryotic cell. They contain their own mitochondrial genome, which as a consequence of gradual reduction during evolution typically contains less than two dozens of genes. In this review, we highlight the extremely diverse architecture of mitochondrial genomes and mechanisms of gene expression between the three sister groups constituting the phylum Euglenozoa - Euglenida, Diplonemea and Kinetoplastea. The earliest diverging euglenids possess a simplified mitochondrial genome and a conventional gene expression, whereas both are highly complex in the two other groups. The expression of their mitochondrial-encoded proteins requires extensive post-transcriptional modifications guided by complex protein machineries and multiple small RNA molecules. Moreover, the least studied diplonemids, which have been recently discovered as a highly abundant component of the ...
Perkinsela is an enigmatic early-branching kinetoplastid protist that lives as an obligate endosy... more Perkinsela is an enigmatic early-branching kinetoplastid protist that lives as an obligate endosymbiont inside Paramoeba (Amoebozoa). We have sequenced the highly reduced mitochondrial genome of Perkinsela, which possesses only six protein-coding genes (cox1, cox2, cox3, cob, atp6, and rps12), despite the fact that the organelle itself contains more DNA than is present in either the host or endosymbiont nuclear genomes. An in silico analysis of two Perkinsela strains showed that mitochondrial RNA editing and processing machineries typical of kinetoplastid flagellates are generally conserved, and all mitochondrial transcripts undergo U-insertion/deletion editing. Canonical kinetoplastid mitochondrial ribosomes are also present. We have developed software tools for accurate and exhaustive mapping of transcriptome sequencing (RNA-seq) reads with extensive U-insertions/deletions, which allows detailed investigation of RNA editing via deep sequencing. With these methods, we show that up ...
ABSTRACTTrypanosomatid parasites are significant causes of human disease and are ubiquitous in in... more ABSTRACTTrypanosomatid parasites are significant causes of human disease and are ubiquitous in insects. Despite the importance ofDrosophila melanogasteras a model of infection and immunity and a long awareness that trypanosomatid infection is common in the genus, no trypanosomatid parasites naturally infectingDrosophilahave been characterized. Here, we establish a new model of trypanosomatid infection inDrosophila—Jaenimonas drosophilae, gen. et sp. nov. As far as we are aware, this is the firstDrosophila-parasitic trypanosomatid to be cultured and characterized. Through experimental infections, we find thatDrosophila falleni, the natural host, is highly susceptible to infection, leading to a substantial decrease in host fecundity.J. drosophilaehas a broad host range, readily infecting a number ofDrosophilaspecies, includingD. melanogaster, with oral infection ofD. melanogasterlarvae resulting in the induction of numerous immune genes. When injected into adult hemolymph,J. drosophil...
Host-parasite relationships and parasite biodiversity have been the center of attention for many ... more Host-parasite relationships and parasite biodiversity have been the center of attention for many years; however the primary data obtained from large-scale studies remain scarce. Our long term investigations of trypanosomatid (Euglenozoa: Kinetoplastea) biodiversity from Neotropical Heteroptera have yielded almost one hundred typing units (TU) of trypanosomatids from one hundred twenty host species. Half of the parasites' TUs were documented in a single host species only but the rest were found parasitizing two to nine species of hosts, with logarithmic distribution best describing the observed distribution of parasites among hosts. Different host superfamilies did not show significant differences in numbers of trypanosomatid TUs they carry, with exception of Pyrrhocoroidea which showed higher parasite richness than any other group tested. Predatory reduviids shared significantly larger numbers of parasite TUs with phytophagous mirids and coreids than the numbers shared between any other groups. These results show that the specificity of trypanosomatid-heteropteran associations is not very strict: parasites seem to be transmissible between different host groups within the same niche and predatory hosts may acquire parasites from their prey.
The Journal of eukaryotic microbiology, Jan 9, 2015
In this study, we surveyed six species of cockroaches, two synanthropic (i.e. ecologically associ... more In this study, we surveyed six species of cockroaches, two synanthropic (i.e. ecologically associated with humans) and four wild, for intestinal trypanosomatid infections. Only the wild cockroach species were found to be infected, with flagellates of the genus Herpetomonas. Two distinct genotypes were documented, one of which was described as a new species, Herpetomonas tarakana sp. n. We also propose a revision of the genus Herpetomonas and creation of a new subfamily, Phytomonadinae, to include Herpetomonas, Phytomonas, and a newly described genus Lafontella n. gen. (type species Lafontella mariadeanei comb. n.), which can be distinguished from others by morphological and molecular traits.
Proceedings of the National Academy of Sciences of the United States of America, Jan 21, 2015
Sexual reproduction and clonality in eukaryotes are mostly seen as exclusive, the latter being ra... more Sexual reproduction and clonality in eukaryotes are mostly seen as exclusive, the latter being rather exceptional. This view might be biased by focusing almost exclusively on metazoans. We analyze and discuss reproduction in the context of extant eukaryotic diversity, paying special attention to protists. We present results of phylogenetically extended searches for homologs of two proteins functioning in cell and nuclear fusion, respectively (HAP2 and GEX1), providing indirect evidence for these processes in several eukaryotic lineages where sex has not been observed yet. We argue that (i) the debate on the relative significance of sex and clonality in eukaryotes is confounded by not appropriately distinguishing multicellular and unicellular organisms; (ii) eukaryotic sex is extremely widespread and already present in the last eukaryotic common ancestor; and (iii) the general mode of existence of eukaryotes is best described by clonally propagating cell lines with episodic sex trigg...
It is timely to evaluate the role of protozoa as model organisms given their diversity, abundance... more It is timely to evaluate the role of protozoa as model organisms given their diversity, abundance and versatility as well as the economic and ethical pressures placed on animal-based experimentation. We first define the term model organism and then examine through examples why protozoa make good models. Our examples reflect major issues including evolution, ecology, population and community biology, disease, the role of organelles, ageing, space travel, toxicity and teaching. We conclude by recognising that although protozoa may in some cases not completely mimic tissue- or whole-animal-level processes, they are extremely flexible and their use should be embraced. Finally, we offer advice on obtaining emergent model protozoa.
Previously, scientists sometimes resorted to infecting themselves or colleagues with parasites, u... more Previously, scientists sometimes resorted to infecting themselves or colleagues with parasites, usually to assess the pathogenicity and obtain insight into the life cycles of the parasites, host specificity, and epidemiology. However, with recent research addressing the possible beneficial impact of intestinal helminths on a range of immune-mediated diseases in humans, these studies offer valuable information, although many are now considered unethical owing to a lack of experimental oversight and informed consent. Here, we critically review cases in which humans were deliberately infected with parasites. Moreover, we summarize the contribution of (self-) infections and propose protist and helminth candidates, chosen on the basis of several criteria, to test as possible therapy for selected human diseases.
Here we report that trypanosomatid flagellates of the genus Blastocrithidia possess catalase. Thi... more Here we report that trypanosomatid flagellates of the genus Blastocrithidia possess catalase. This enzyme is not phylogenetically related to the previously characterized catalases in other monoxenous trypanosomatids, suggesting that their genes have been acquired independently. Surprisingly, Blastocrithidia catalase is less enzymatically active, compared to its counterpart from Leptomonas pyrrhocoris, posing an intriguing biological question why this gene has been retained in the evolution of trypanosomatids.
Fe-S clusters are ubiquitous cofactors of proteins involved in a variety of essential cellular pr... more Fe-S clusters are ubiquitous cofactors of proteins involved in a variety of essential cellular processes. The biogenesis of Fe-S clusters in the cytosol and their insertion into proteins is accomplished through the cytosolic iron-sulphur protein assembly (CIA) machinery. The early- and middle-acting modules of the CIA pathway concerned with the assembly and trafficking of Fe-S clusters have been previously characterised in the parasitic protist Trypanosoma brucei. In this study, we applied proteomic and genetic approaches to gain insights into the network of protein-protein interactions of the late-acting CIA targeting complex in T. brucei. All components of the canonical CIA machinery are present in T. brucei including, as in humans, two distinct CIA2 homologues TbCIA2A and TbCIA2B. These two proteins are found interacting with TbCIA1, yet the interaction is mutually exclusive, as determined by mass spectrometry. Ablation of most of the components of the CIA targeting complex by RN...
Mitochondria are double membrane organelles of endosymbiotic origin, best known for constituting ... more Mitochondria are double membrane organelles of endosymbiotic origin, best known for constituting the centre of energetics of a eukaryotic cell. They contain their own mitochondrial genome, which as a consequence of gradual reduction during evolution typically contains less than two dozens of genes. In this review, we highlight the extremely diverse architecture of mitochondrial genomes and mechanisms of gene expression between the three sister groups constituting the phylum Euglenozoa - Euglenida, Diplonemea and Kinetoplastea. The earliest diverging euglenids possess a simplified mitochondrial genome and a conventional gene expression, whereas both are highly complex in the two other groups. The expression of their mitochondrial-encoded proteins requires extensive post-transcriptional modifications guided by complex protein machineries and multiple small RNA molecules. Moreover, the least studied diplonemids, which have been recently discovered as a highly abundant component of the ...
Perkinsela is an enigmatic early-branching kinetoplastid protist that lives as an obligate endosy... more Perkinsela is an enigmatic early-branching kinetoplastid protist that lives as an obligate endosymbiont inside Paramoeba (Amoebozoa). We have sequenced the highly reduced mitochondrial genome of Perkinsela, which possesses only six protein-coding genes (cox1, cox2, cox3, cob, atp6, and rps12), despite the fact that the organelle itself contains more DNA than is present in either the host or endosymbiont nuclear genomes. An in silico analysis of two Perkinsela strains showed that mitochondrial RNA editing and processing machineries typical of kinetoplastid flagellates are generally conserved, and all mitochondrial transcripts undergo U-insertion/deletion editing. Canonical kinetoplastid mitochondrial ribosomes are also present. We have developed software tools for accurate and exhaustive mapping of transcriptome sequencing (RNA-seq) reads with extensive U-insertions/deletions, which allows detailed investigation of RNA editing via deep sequencing. With these methods, we show that up ...
ABSTRACTTrypanosomatid parasites are significant causes of human disease and are ubiquitous in in... more ABSTRACTTrypanosomatid parasites are significant causes of human disease and are ubiquitous in insects. Despite the importance ofDrosophila melanogasteras a model of infection and immunity and a long awareness that trypanosomatid infection is common in the genus, no trypanosomatid parasites naturally infectingDrosophilahave been characterized. Here, we establish a new model of trypanosomatid infection inDrosophila—Jaenimonas drosophilae, gen. et sp. nov. As far as we are aware, this is the firstDrosophila-parasitic trypanosomatid to be cultured and characterized. Through experimental infections, we find thatDrosophila falleni, the natural host, is highly susceptible to infection, leading to a substantial decrease in host fecundity.J. drosophilaehas a broad host range, readily infecting a number ofDrosophilaspecies, includingD. melanogaster, with oral infection ofD. melanogasterlarvae resulting in the induction of numerous immune genes. When injected into adult hemolymph,J. drosophil...
Host-parasite relationships and parasite biodiversity have been the center of attention for many ... more Host-parasite relationships and parasite biodiversity have been the center of attention for many years; however the primary data obtained from large-scale studies remain scarce. Our long term investigations of trypanosomatid (Euglenozoa: Kinetoplastea) biodiversity from Neotropical Heteroptera have yielded almost one hundred typing units (TU) of trypanosomatids from one hundred twenty host species. Half of the parasites' TUs were documented in a single host species only but the rest were found parasitizing two to nine species of hosts, with logarithmic distribution best describing the observed distribution of parasites among hosts. Different host superfamilies did not show significant differences in numbers of trypanosomatid TUs they carry, with exception of Pyrrhocoroidea which showed higher parasite richness than any other group tested. Predatory reduviids shared significantly larger numbers of parasite TUs with phytophagous mirids and coreids than the numbers shared between any other groups. These results show that the specificity of trypanosomatid-heteropteran associations is not very strict: parasites seem to be transmissible between different host groups within the same niche and predatory hosts may acquire parasites from their prey.
The Journal of eukaryotic microbiology, Jan 9, 2015
In this study, we surveyed six species of cockroaches, two synanthropic (i.e. ecologically associ... more In this study, we surveyed six species of cockroaches, two synanthropic (i.e. ecologically associated with humans) and four wild, for intestinal trypanosomatid infections. Only the wild cockroach species were found to be infected, with flagellates of the genus Herpetomonas. Two distinct genotypes were documented, one of which was described as a new species, Herpetomonas tarakana sp. n. We also propose a revision of the genus Herpetomonas and creation of a new subfamily, Phytomonadinae, to include Herpetomonas, Phytomonas, and a newly described genus Lafontella n. gen. (type species Lafontella mariadeanei comb. n.), which can be distinguished from others by morphological and molecular traits.
Proceedings of the National Academy of Sciences of the United States of America, Jan 21, 2015
Sexual reproduction and clonality in eukaryotes are mostly seen as exclusive, the latter being ra... more Sexual reproduction and clonality in eukaryotes are mostly seen as exclusive, the latter being rather exceptional. This view might be biased by focusing almost exclusively on metazoans. We analyze and discuss reproduction in the context of extant eukaryotic diversity, paying special attention to protists. We present results of phylogenetically extended searches for homologs of two proteins functioning in cell and nuclear fusion, respectively (HAP2 and GEX1), providing indirect evidence for these processes in several eukaryotic lineages where sex has not been observed yet. We argue that (i) the debate on the relative significance of sex and clonality in eukaryotes is confounded by not appropriately distinguishing multicellular and unicellular organisms; (ii) eukaryotic sex is extremely widespread and already present in the last eukaryotic common ancestor; and (iii) the general mode of existence of eukaryotes is best described by clonally propagating cell lines with episodic sex trigg...
It is timely to evaluate the role of protozoa as model organisms given their diversity, abundance... more It is timely to evaluate the role of protozoa as model organisms given their diversity, abundance and versatility as well as the economic and ethical pressures placed on animal-based experimentation. We first define the term model organism and then examine through examples why protozoa make good models. Our examples reflect major issues including evolution, ecology, population and community biology, disease, the role of organelles, ageing, space travel, toxicity and teaching. We conclude by recognising that although protozoa may in some cases not completely mimic tissue- or whole-animal-level processes, they are extremely flexible and their use should be embraced. Finally, we offer advice on obtaining emergent model protozoa.
Previously, scientists sometimes resorted to infecting themselves or colleagues with parasites, u... more Previously, scientists sometimes resorted to infecting themselves or colleagues with parasites, usually to assess the pathogenicity and obtain insight into the life cycles of the parasites, host specificity, and epidemiology. However, with recent research addressing the possible beneficial impact of intestinal helminths on a range of immune-mediated diseases in humans, these studies offer valuable information, although many are now considered unethical owing to a lack of experimental oversight and informed consent. Here, we critically review cases in which humans were deliberately infected with parasites. Moreover, we summarize the contribution of (self-) infections and propose protist and helminth candidates, chosen on the basis of several criteria, to test as possible therapy for selected human diseases.
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Papers by Julius Lukeš