scholarly journals Cancer in the parasitic protozoans Trypanosoma brucei and Toxoplasma gondii

2015 ◽  
Vol 112 (29) ◽  
pp. 8835-8842 ◽  
Author(s):  
Zhao-Rong Lun ◽  
De-Hua Lai ◽  
Yan-Zi Wen ◽  
Ling-Ling Zheng ◽  
Ji-Long Shen ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Trypanosoma Brucei ◽  
Severe Disease ◽  
Life Cycles ◽  
Model Systems ◽  
Suitable Model ◽  
Complex Life Cycles ◽  
Obligate Intracellular ◽  
Obligate Intracellular Pathogen ◽  
Made In

Cancer is a general name for more than 100 malignant diseases. It is postulated that all cancers start from a single abnormal cell that grows out of control. Untreated cancers can cause serious consequences and deaths. Great progress has been made in cancer research that has significantly improved our knowledge and understanding of the nature and mechanisms of the disease, but the origins of cancer are far from being well understood due to the limitations of suitable model systems and to the complexities of the disease. In view of the fact that cancers are found in various species of vertebrates and other metazoa, here, we suggest that cancer also occurs in parasitic protozoans such as Trypanosoma brucei, a blood parasite, and Toxoplasma gondii, an obligate intracellular pathogen. Without treatment, these protozoan cancers may cause severe disease and death in mammals, including humans. The simpler genomes of these single-cell organisms, in combination with their complex life cycles and fascinating life cycle differentiation processes, may help us to better understand the origins of cancers and, in particular, leukemias.

scholarly journals Determinants and consequences of dispersal in vertebrates with complex life cycles: a review of pond-breeding amphibians

2018 ◽  
Author(s):  
Hugo Cayuela ◽  
Andrés Valenzuela-Sanchez ◽  
Loïc Teulier ◽  
Íñigo Martínez-Solano ◽  
Jean-Paul Léna ◽  
...  
Keyword(s):  
Evolutionary Dynamics ◽  
Current Knowledge ◽  
Life Cycles ◽  
Structured Populations ◽  
Model Systems ◽  
Suitable Model ◽  
Dispersal Patterns ◽  
Central Process ◽  
Complex Life Cycles ◽  
Spatially Structured Populations

Dispersal is a central process in ecology and evolution. It strongly influences the dynamics of spatially structured populations, by affecting population growth rate and local colonization-extinction processes. Dispersal can also influence evolutionary processes because it determines rates and patterns of gene flow in spatially structured populations and is closely linked to local adaptation. For these reasons, dispersal has received considerable attention from ecologists and evolutionary biologists. However, although it has been studied extensively in taxa such as birds and mammals, much less is known about dispersal in vertebrates with complex life cycles such as pond-breeding amphibians. Over the past two decades, researchers have taken an interest in amphibian dispersal and initiated both fundamental and applied studies, using a broad range of experimental and observational approaches. This body of research reveals complex dispersal patterns, causations and syndromes, with dramatic consequences for the demography and genetics of amphibian populations. In this review, our goals are to (1) redefine and clarify the concept of amphibian dispersal, (2) review current knowledge about the effects of individual (i.e., condition-dependent dispersal) and environmental (i.e., context-dependent dispersal) factors during the three stages of dispersal (i.e., emigration, immigration, transience), (3) identify the demographic and genetic consequences of dispersal in spatially structured amphibian populations, and (4) propose new research avenues to extend our understanding of amphibian dispersal. In particular, we emphasize the need to (1) quantify dispersal rate and distance rigorously using suitable model systems, (2) investigate the genetic basis and dispersal evolution patterns, and (3) examine dispersal-related eco-evolutionary dynamics. These proposed research avenues tap from the recent advances in quantitative and molecular methods and have the potential to improve our understanding of dispersal in organisms with complex life cycles.

scholarly journals Determinants and consequences of dispersal in vertebrates with complex life cycles: a review of pond-breeding amphibians

2018 ◽  
Author(s):  
Hugo Cayuela ◽  
Andrés Valenzuela-Sanchez ◽  
Loïc Teulier ◽  
Íñigo Martínez-Solano ◽  
Jean-Paul Léna ◽  
...  
Keyword(s):  
Evolutionary Dynamics ◽  
Current Knowledge ◽  
Life Cycles ◽  
Structured Populations ◽  
Model Systems ◽  
Suitable Model ◽  
Dispersal Patterns ◽  
Central Process ◽  
Complex Life Cycles ◽  
Spatially Structured Populations

Dispersal is a central process in ecology and evolution. It strongly influences the dynamics of spatially structured populations, by affecting population growth rate and local colonization-extinction processes. Dispersal can also influence evolutionary processes because it determines rates and patterns of gene flow in spatially structured populations and is closely linked to local adaptation. For these reasons, dispersal has received considerable attention from ecologists and evolutionary biologists. However, although it has been studied extensively in taxa such as birds and mammals, much less is known about dispersal in vertebrates with complex life cycles such as pond-breeding amphibians. Over the past two decades, researchers have taken an interest in amphibian dispersal and initiated both fundamental and applied studies, using a broad range of experimental and observational approaches. This body of research reveals complex dispersal patterns, causations and syndromes, with dramatic consequences for the demography and genetics of amphibian populations. In this review, our goals are to (1) redefine and clarify the concept of amphibian dispersal, (2) review current knowledge about the effects of individual (i.e., condition-dependent dispersal) and environmental (i.e., context-dependent dispersal) factors during the three stages of dispersal (i.e., emigration, immigration, transience), (3) identify the demographic and genetic consequences of dispersal in spatially structured amphibian populations, and (4) propose new research avenues to extend our understanding of amphibian dispersal. In particular, we emphasize the need to (1) quantify dispersal rate and distance rigorously using suitable model systems, (2) investigate the genetic basis and dispersal evolution patterns, and (3) examine dispersal-related eco-evolutionary dynamics. These proposed research avenues tap from the recent advances in quantitative and molecular methods and have the potential to improve our understanding of dispersal in organisms with complex life cycles.

Effect of conspecifics density on the settlement of Petrolisthes laevigatus (Decapoda: Porcellanidae)

2011 ◽  
Vol 91 (7) ◽  
pp. 1453-1458 ◽  
Author(s):  
P. Gebauer ◽  
M. Freire ◽  
A. Barria ◽  
K. Paschke
Keyword(s):  
Size Distribution ◽  
Critical Points ◽  
Marine Invertebrates ◽  
Spatial Scales ◽  
Coastal Areas ◽  
Life Cycles ◽  
Settlement Rate ◽  
Complex Life Cycles ◽  
Second Year ◽  
Made In

Settlement is one of the critical points in the development of organisms with complex life cycles. Some marine invertebrates respond to specific cues such as substratum and conspecifics, and the larvae of species presenting gregarious settlement are characterized by a preference for settlement in patches with conspecifics over those without. An evaluation was made in the field of the effect of conspecifics density on the settlement of Petrolisthes laevigatus during two settlement seasons. The size-distribution and density were maintained constant throughout the first settlement season, while in the second year they were adjusted to match those presented in three previously identified periods during the season. The settlement rate of P. laevigatus was higher in the presence than the absence of conspecifics. There was evidence of saturation in the settlement of the higher densities, mainly at the beginning of the settlement season, when approximately 80% of the settlement occurred. We propose that gregarious settlement is an important factor in determining the distribution and abundance of P. laevigatus at different spatial scales, both within and among coastal areas, and could restrict the colonization of new areas and the recovery of populations reduced by disturbances.

scholarly journals Host-derived glucose and its transporter in the obligate intracellular pathogen Toxoplasma gondii are dispensable by glutaminolysis

2009 ◽  
Vol 106 (31) ◽  
pp. 12998-13003 ◽  
Author(s):  
M. Blume ◽  
D. Rodriguez-Contreras ◽  
S. Landfear ◽  
T. Fleige ◽  
D. Soldati-Favre ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Intracellular Pathogen ◽  
Obligate Intracellular ◽  
Obligate Intracellular Pathogen

scholarly journals Lytic Cycle of Toxoplasma gondii

2000 ◽  
Vol 64 (3) ◽  
pp. 607-623 ◽  
Author(s):  
Michael W. Black ◽  
John C. Boothroyd
Keyword(s):  
Toxoplasma Gondii ◽  
Current Knowledge ◽  
Protozoan Parasite ◽  
Geographic Range ◽  
Lytic Cycle ◽  
Broad Host Range ◽  
Intracellular Pathogen ◽  
Obligate Intracellular ◽  
Obligate Intracellular Pathogen ◽  
Serious Disease

SUMMARY Toxoplasma gondii is an obligate intracellular pathogen within the phylum Apicomplexa. This protozoan parasite is one of the most widespread, with a broad host range including many birds and mammals and a geographic range that is nearly worldwide. While infection of healthy adults is usually relatively mild, serious disease can result in utero or when the host is immunocompromised. This sophisticated eukaryote has many specialized features that make it well suited to its intracellular lifestyle. In this review, we describe the current knowledge of how the asexual tachyzoite stage of Toxoplasma attaches to, invades, replicates in, and exits the host cell. Since this process is closely analogous to the way in which viruses reproduce, we refer to it as the Toxoplasma “lytic cycle.”

scholarly journals When should a trophically and vertically transmitted parasite manipulate its intermediate host? The case of Toxoplasma gondii

2013 ◽  
Vol 280 (1765) ◽  
pp. 20131143 ◽  
Author(s):  
Maud Lélu ◽  
Michel Langlais ◽  
Marie-Lazarine Poulle ◽  
Emmanuelle Gilot-Fromont ◽  
Sylvain Gandon
Keyword(s):  
Toxoplasma Gondii ◽  
Vertical Transmission ◽  
Death Rate ◽  
Predation Rate ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Complex Life Cycles ◽  
Virulent Strains ◽  
Host Behaviour ◽  
Different Levels

Parasites with complex life cycles are expected to manipulate the behaviour of their intermediate hosts (IHs), which increase their predation rate and facilitate the transmission to definitive hosts (DHs). This ability, however, is a double-edged sword when the parasite can also be transmitted vertically in the IH. In this situation, as the manipulation of the IH behaviour increases the IH death rate, it conflicts with vertical transmission, which requires healthy and reproducing IHs. The protozoan Toxoplasma gondii , a widespread pathogen, combines both trophic and vertical transmission strategies. Is parasite manipulation of host behaviour still adaptive in this situation? We model the evolution of the IH manipulation by T. gondii to study the conflict between these two routes of transmission under different epidemiological situations. Model outputs show that manipulation is particularly advantageous for virulent strains and in epidemic situations, and that different levels of manipulation may evolve depending on the sex of the IH and the transmission routes considered. These results may help to understand the variability of strain characteristics encountered for T. gondii and may extend to other trophically transmitted parasites.

Coordination of the Cell Cycle in Trypanosomes

2019 ◽  
Vol 73 (1) ◽  
pp. 133-154 ◽  
Author(s):  
Richard J. Wheeler ◽  
Keith Gull ◽  
Jack D. Sunter
Keyword(s):  
Cell Cycle ◽  
Life Cycle ◽  
Trypanosoma Brucei ◽  
Cross Talk ◽  
Life Cycle Stage ◽  
Life Cycles ◽  
Complex Life Cycles ◽  
Cell Divisions ◽  
Proliferative Cell

Trypanosomes have complex life cycles within which there are both proliferative and differentiation cell divisions. The coordination of the cell cycle to achieve these different divisions is critical for the parasite to infect both host and vector. From studying the regulation of the proliferative cell cycle of the Trypanosoma brucei procyclic life cycle stage, three subcycles emerge that control the duplication and segregation of ( a) the nucleus, ( b) the kinetoplast, and ( c) a set of cytoskeletal structures. We discuss how the clear dependency relationships within these subcycles, and the potential for cross talk between them, are likely required for overall cell cycle coordination. Finally, we look at the implications this interdependence has for proliferative and differentiation divisions through the T. brucei life cycle and in related parasitic trypanosomatid species.

scholarly journals Untargeted Metabolomics Uncovers the Essential Lysine Transporter in Toxoplasma gondii

Metabolites ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 476
Author(s):  
Joachim Kloehn ◽  
Matteo Lunghi ◽  
Emmanuel Varesio ◽  
David Dubois ◽  
Dominique Soldati-Favre
Keyword(s):  
Amino Acids ◽  
Toxoplasma Gondii ◽  
Rna Degradation ◽  
Major Facilitator Superfamily ◽  
Untargeted Metabolomics ◽  
Apicomplexan Parasites ◽  
Obligate Intracellular ◽  
Intracellular Parasites ◽  
Major Facilitator ◽  
Plasma Membrane Transporter

Apicomplexan parasites are responsible for devastating diseases, including malaria, toxoplasmosis, and cryptosporidiosis. Current treatments are limited by emerging resistance to, as well as the high cost and toxicity of existing drugs. As obligate intracellular parasites, apicomplexans rely on the uptake of many essential metabolites from their host. Toxoplasma gondii, the causative agent of toxoplasmosis, is auxotrophic for several metabolites, including sugars (e.g., myo-inositol), amino acids (e.g., tyrosine), lipidic compounds and lipid precursors (cholesterol, choline), vitamins, cofactors (thiamine) and others. To date, only few apicomplexan metabolite transporters have been characterized and assigned a substrate. Here, we set out to investigate whether untargeted metabolomics can be used to identify the substrate of an uncharacterized transporter. Based on existing genome- and proteome-wide datasets, we have identified an essential plasma membrane transporter of the major facilitator superfamily in T. gondii—previously termed TgApiAT6-1. Using an inducible system based on RNA degradation, TgApiAT6-1 was depleted, and the mutant parasite’s metabolome was compared to that of non-depleted parasites. The most significantly reduced metabolite in parasites depleted in TgApiAT6-1 was identified as the amino acid lysine, for which T. gondii is predicted to be auxotrophic. Using stable isotope-labeled amino acids, we confirmed that TgApiAT6-1 is required for efficient lysine uptake. Our findings highlight untargeted metabolomics as a powerful tool to identify the substrate of orphan transporters.

scholarly journals Impacts of climate change on the complex life cycles of fish

2012 ◽  
Vol 22 (2) ◽  
pp. 121-139 ◽  
Author(s):  
Pierre Petitgas ◽  
Adriaan D. Rijnsdorp ◽  
Mark Dickey-Collas ◽  
Georg H. Engelhard ◽  
Myron A. Peck ◽  
...  
Keyword(s):  
Climate Change ◽  
Life Cycles ◽  
Complex Life Cycles ◽  
Impacts Of Climate Change

Complex Life Cycles: Why Refrain from Growth before Reproduction in the Adult Niche?

2013 ◽  
Vol 181 (1) ◽  
pp. 39-51 ◽  
Author(s):  
Daniel P. Benesh ◽  
James C. Chubb ◽  
Geoff A. Parker
Keyword(s):  
Life Cycles ◽  
Complex Life Cycles
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