scholarly journals Timing and original features of flagellum assembly in trypanosomes during development in the tsetse fly

2019 ◽  
Author(s):  
Moara Lemos ◽  
Adeline Mallet ◽  
Eloïse Bertiaux ◽  
Albane Imbert ◽  
Brice Rotureau ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Life Cycle ◽  
Trypanosoma Brucei ◽  
Tsetse Fly ◽  
The Body ◽  
Complex Life Cycle ◽  
Tsetse Flies ◽  
Molecular Evidence ◽  
Morphological Development ◽  
Sequence Of Events

AbstractTrypanosoma brucei exhibits a complex life cycle alternating between tsetse flies and mammalian hosts. When parasites infect the fly, cells differentiate to adapt to life in various tissues, which is accompanied by drastic morphological and biochemical modifications especially in the proventriculus. This key step represents a bottleneck for salivary gland infection. Here we monitored flagellum assembly in trypanosomes during differentiation from the trypomastigote to the epimastigote stage, i.e. when the nucleus migrates to the posterior end of the cell. Three-dimensional electron microscopy (Focused Ion Bean Scanning Electron Microscopy, FIB-SEM) and immunofluorescence assays provided structural and molecular evidence that the new flagellum is assembled while the nucleus migrates towards the posterior region of the body. Two major differences with well known procyclic cells are reported. First, growth of the new flagellum begins when the associated basal body is found in a posterior position relative to the mature one. Second, the new flagellum acquires its own flagellar pocket before rotating on the left side of the anterior-posterior axis. FIB-SEM revealed the presence of a structure connecting the new and mature flagellum and serial sectioning confirmed morphological similarities with the flagella connector of procyclic cells. We discuss potential function of the flagella connector in trypanosomes from the proventriculus. These findings show that T. brucei finely modulates its cytoskeletal components to generate highly variable morphologies.Author SummaryTrypanosoma brucei is a flagellated parasitic protist that causes human African trypanosomiasis, or sleeping sickness and that is transmitted by the bite of tsetse flies. The complex life cycle of T. brucei inside the tsetse digestive tract requires adaptation to specific organs and follow a strictly defined order. It is marked by morphological modifications in cell shape and size, as well organelle positioning. In the proventriculus of tsetse flies, T. brucei undergoes a unique asymmetric division leading to two very different daughter cells: one with a short and one with a long flagellum. This organelle is crucial for the trypanosome life cycle as it is involved in motility, adhesion and morphogenesis. Here we investigated flagellum assembly using molecular and 3D Electron Microscopy approaches revealing that flagellum construction in proventricular trypanosomes is concomitant with parasite differentiation. During flagellum growth, the new flagellum is connected to the mature one and rotates around the mature one after its emergence at the cell surface. The sequence of events is different from what is observed in the well-studied procyclic stage in culture revealing different processes governing morphological development. These results highlight the importance to study pathogen development in their natural environment.

scholarly journals Intraflagellar transport during the assembly of flagella of different length in Trypanosoma brucei isolated from tsetse flies

2020 ◽  
Author(s):  
Eloïse Bertiaux ◽  
Adeline Mallet ◽  
Brice Rotureau ◽  
Philippe Bastin
Keyword(s):  
Life Cycle ◽  
Trypanosoma Brucei ◽  
Live Cell Imaging ◽  
Intraflagellar Transport ◽  
Tsetse Fly ◽  
Tsetse Flies ◽  
Life Cycle Stages ◽  
Summary Statement ◽  
Cilia And Flagella ◽  
Multicellular Organisms

AbstractMulticellular organisms assemble cilia and flagella of precise lengths differing from one cell to another, yet little is known about the mechanisms governing these differences. Similarly, protists assemble flagella of different lengths according to the stage of their life cycle. This is the case of Trypanosoma brucei that assembles flagella of 3 to 30 µm during its development in the tsetse fly. It provides an opportunity to examine how cells naturally modulate organelle length. Flagella are constructed by addition of new blocks at their distal end via intraflagellar transport (IFT). Immunofluorescence assays, 3-D electron microscopy and live cell imaging revealed that IFT was present in all life cycle stages. IFT proteins are concentrated at the base, IFT trains are located along doublets 3-4 & 7-8 and travel bidirectionally in the flagellum. Quantitative analysis demonstrated that the total amount of IFT proteins correlates with the length of the flagellum. Surprisingly, the shortest flagellum exhibited a supplementary large amount of dynamic IFT material at its distal end. The contribution of IFT and other factors to the regulation of flagellum length is discussed.Summary statementThis work investigated the assembly of flagella of different length during the development of Trypanosoma brucei in the tsetse fly, revealing a direct correlation between the amount of intraflagellar transport proteins and flagellum length.

scholarly journals Unexpected plasticity in the life cycle of Trypanosoma brucei

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Sarah Schuster ◽  
Jaime Lisack ◽  
Ines Subota ◽  
Henriette Zimmermann ◽  
Christian Reuter ◽  
...  
Keyword(s):  
Life Cycle ◽  
Trypanosoma Brucei ◽  
Parasite Load ◽  
Tsetse Fly ◽  
Productive Infection ◽  
Complex Life Cycle ◽  
Chronic Infections ◽  
Population Densities ◽  
African Trypanosomes ◽  
Stage Transition

African trypanosomes cause sleeping sickness in humans and nagana in cattle. These unicellular parasites are transmitted by the bloodsucking tsetse fly. In the mammalian host's circulation, proliferating slender stage cells differentiate into cell cycle-arrested stumpy stage cells when they reach high population densities. This stage transition is thought to fulfil two main functions: first, it auto-regulates the parasite load in the host; second, the stumpy stage is regarded as the only stage capable of successful vector transmission. Here, we show that proliferating slender stage trypanosomes express the mRNA and protein of a known stumpy stage marker, complete the complex life cycle in the fly as successfully as the stumpy stage, and require only a single parasite for productive infection. These findings suggest a reassessment of the traditional view of the trypanosome life cycle. They may also provide a solution to a long-lasting paradox, namely the successful transmission of parasites in chronic infections, despite low parasitemia.

scholarly journals Intraflagellar transport during assembly of flagella of different length in Trypanosoma brucei isolated from tsetse flies

2020 ◽  
Vol 133 (18) ◽  
pp. jcs248989
Author(s):  
Eloïse Bertiaux ◽  
Adeline Mallet ◽  
Brice Rotureau ◽  
Philippe Bastin
Keyword(s):  
Life Cycle ◽  
Trypanosoma Brucei ◽  
Live Cell Imaging ◽  
Intraflagellar Transport ◽  
Tsetse Fly ◽  
Tsetse Flies ◽  
Life Cycle Stages ◽  
3D Electron Microscopy ◽  
Cilia And Flagella ◽  
Multicellular Organisms

ABSTRACTMulticellular organisms assemble cilia and flagella of precise lengths differing from one cell to another, yet little is known about the mechanisms governing these differences. Similarly, protists assemble flagella of different lengths according to the stage of their life cycle. Trypanosoma brucei assembles flagella of 3 to 30 µm during its development in the tsetse fly. This provides an opportunity to examine how cells naturally modulate organelle length. Flagella are constructed by addition of new blocks at their distal end via intraflagellar transport (IFT). Immunofluorescence assays, 3D electron microscopy and live-cell imaging revealed that IFT was present in all T. brucei life cycle stages. IFT proteins are concentrated at the base, and IFT trains are located along doublets 3–4 and 7–8 and travel bidirectionally in the flagellum. Quantitative analysis demonstrated that the total amount of flagellar IFT proteins correlates with the length of the flagellum. Surprisingly, the shortest flagellum exhibited a supplementary large amount of dynamic IFT material at its distal end. The contribution of IFT and other factors to the regulation of flagellum length is discussed.

scholarly journals Positional Dynamics and Glycosomal Recruitment of Developmental Regulators during Trypanosome Differentiation

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Balázs Szöőr ◽  
Dorina V. Simon ◽  
Federico Rojas ◽  
Julie Young ◽  
Derrick R. Robinson ◽  
...  
Keyword(s):  
Life Cycle ◽  
Trypanosoma Brucei ◽  
Tyrosine Phosphatase ◽  
Tsetse Fly ◽  
Sub Saharan Africa ◽  
Metabolic Adaptation ◽  
Tsetse Flies ◽  
Content Type ◽  
African Trypanosomes ◽  
Sub Saharan

ABSTRACT Glycosomes are peroxisome-related organelles that compartmentalize the glycolytic enzymes in kinetoplastid parasites. These organelles are developmentally regulated in their number and composition, allowing metabolic adaptation to the parasite’s needs in the blood of mammalian hosts or within their arthropod vector. A protein phosphatase cascade regulates differentiation between parasite developmental forms, comprising a tyrosine phosphatase, Trypanosoma brucei PTP1 (TbPTP1), which dephosphorylates and inhibits a serine threonine phosphatase, TbPIP39, which promotes differentiation. When TbPTP1 is inactivated, TbPIP39 is activated and during differentiation becomes located in glycosomes. Here we have tracked TbPIP39 recruitment to glycosomes during differentiation from bloodstream “stumpy” forms to procyclic forms. Detailed microscopy and live-cell imaging during the synchronous transition between life cycle stages revealed that in stumpy forms, TbPIP39 is located at a periflagellar pocket site closely associated with TbVAP, which defines the flagellar pocket endoplasmic reticulum. TbPTP1 is also located at the same site in stumpy forms, as is REG9.1, a regulator of stumpy-enriched mRNAs. This site provides a molecular node for the interaction between TbPTP1 and TbPIP39. Within 30 min of the initiation of differentiation, TbPIP39 relocates to glycosomes, whereas TbPTP1 disperses to the cytosol. Overall, the study identifies a “stumpy regulatory nexus” (STuRN) that coordinates the molecular components of life cycle signaling and glycosomal development during transmission of Trypanosoma brucei. IMPORTANCE African trypanosomes are parasites of sub-Saharan Africa responsible for both human and animal disease. The parasites are transmitted by tsetse flies, and completion of their life cycle involves progression through several development steps. The initiation of differentiation between blood and tsetse fly forms is signaled by a phosphatase cascade, ultimately trafficked into peroxisome-related organelles called glycosomes that are unique to this group of organisms. Glycosomes undergo substantial remodeling of their composition and function during the differentiation step, but how this is regulated is not understood. Here we identify a cytological site where the signaling molecules controlling differentiation converge before the dispersal of one of them into glycosomes. In combination, the study provides the first insight into the spatial coordination of signaling pathway components in trypanosomes as they undergo cell-type differentiation.

scholarly journals Unexpected plasticity in the life cycle of Trypanosoma brucei

2019 ◽  
Author(s):  
Sarah Schuster ◽  
Ines Subota ◽  
Jaime Lisack ◽  
Henriette Zimmermann ◽  
Christian Reuter ◽  
...  
Keyword(s):  
Life Cycle ◽  
Parasite Load ◽  
Tsetse Fly ◽  
Productive Infection ◽  
Complex Life Cycle ◽  
Tsetse Flies ◽  
Chronic Infections ◽  
African Trypanosomes ◽  
Life Cycle Stages ◽  
Shed Light

AbstractAfrican trypanosomes cause sleeping sickness in humans and nagana in cattle. These unicellular parasites are transmitted by the bloodsucking tsetse fly. In the mammalian host’s circulation, tissues, and interstitium, at least two main life cycle stages exist: slender and stumpy bloodstream stages. Proliferating slender stage cells differentiate into cell cycle-arrested stumpy stage cells at high population densities. This developmental stage transition occurs in response to the quorum sensing factor SIF (stumpy induction factor), and is thought to fulfil two main functions. First, it auto-regulates the parasite load in the host. Second, the stumpy stage is regarded as pre-adapted for tsetse fly infection and the only stage capable of successful vector transmission. Here, we show that proliferating slender stage trypanosomes are able to complete the complex life cycle in the fly as successfully as the stumpy stage, and that a single parasite is sufficient for productive infection. Our findings not only propose a revision to the traditional rigid view of the trypanosome life cycle, but also suggest a solution to a long-acknowledged paradox in the transmission event: parasitaemia in chronic infections is characteristically low, and so the probability of a tsetse ingesting a stumpy cell during a bloodmeal is also low. The finding that proliferating slender parasites are infective to tsetse flies helps shed light on this enigma.

scholarly journals Metabolic reprogramming during the Trypanosoma brucei life cycle

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 683 ◽  
Author(s):  
Terry K. Smith ◽  
Frédéric Bringaud ◽  
Derek P. Nolan ◽  
Luisa M. Figueiredo
Keyword(s):  
Life Cycle ◽  
Trypanosoma Brucei ◽  
Model Organism ◽  
Protozoan Parasite ◽  
Tsetse Fly ◽  
Metabolic Reprogramming ◽  
Mammalian Host ◽  
Insect Vector ◽  
Environmental Signals ◽  
Cellular Metabolic Activity

Cellular metabolic activity is a highly complex, dynamic, regulated process that is influenced by numerous factors, including extracellular environmental signals, nutrient availability and the physiological and developmental status of the cell. The causative agent of sleeping sickness, Trypanosoma brucei, is an exclusively extracellular protozoan parasite that encounters very different extracellular environments during its life cycle within the mammalian host and tsetse fly insect vector. In order to meet these challenges, there are significant alterations in the major energetic and metabolic pathways of these highly adaptable parasites. This review highlights some of these metabolic changes in this early divergent eukaryotic model organism.

scholarly journals Differential virulence and tsetse fly transmissibility of Trypanosoma congolense and Trypanosoma brucei strains

2017 ◽  
Vol 84 (1) ◽  
Author(s):  
Purity K. Gitonga ◽  
Kariuki Ndung’u ◽  
Grace A. Murilla ◽  
Paul C. Thande ◽  
Florence N. Wamwiri ◽  
...  
Keyword(s):  
Survival Time ◽  
Trypanosoma Brucei ◽  
Acute Infection ◽  
Glossina Pallidipes ◽  
Trypanosoma Congolense ◽  
Tsetse Fly ◽  
Economic Losses ◽  
Entire Group ◽  
Tsetse Flies ◽  
African Countries

African animal trypanosomiasis causes significant economic losses in sub-Saharan African countries because of livestock mortalities and reduced productivity. Trypanosomes, the causative agents, are transmitted by tsetse flies (Glossina spp.). In the current study, we compared and contrasted the virulence characteristics of five Trypanosoma congolense and Trypanosoma brucei isolates using groups of Swiss white mice (n = 6). We further determined the vectorial capacity of Glossina pallidipes, for each of the trypanosome isolates. Results showed that the overall pre-patent (PP) periods were 8.4 ± 0.9 (range, 4–11) and 4.5 ± 0.2 (range, 4–6) for T. congolense and T. brucei isolates, respectively (p < 0.01). Despite the longer mean PP, T. congolense–infected mice exhibited a significantly (p < 0.05) shorter survival time than T. brucei–infected mice, indicating greater virulence. Differences were also noted among the individual isolates with T. congolense KETRI 2909 causing the most acute infection of the entire group with a mean ± standard error survival time of 9 ± 2.1 days. Survival time of infected tsetse flies and the proportion with mature infections at 30 days post-exposure to the infective blood meals varied among isolates, with subacute infection–causing T. congolense EATRO 1829 and chronic infection–causing T. brucei EATRO 2267 isolates showing the highest mature infection rates of 38.5% and 23.1%, respectively. Therefore, our study provides further evidence of occurrence of differences in virulence and transmissibility of eastern African trypanosome strains and has identified two, T. congolense EATRO 1829 and T. brucei EATRO 2267, as suitable for tsetse infectivity and transmissibility experiments.

scholarly journals Prevalence of Cattle Trypanosomosis and Apparent Density of Its Fly Vectors in Bambasi District of Benishangul-Gumuz Regional State, Western Ethiopia

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Morka Amante ◽  
Hika Tesgera
Keyword(s):  
Trypanosoma Brucei ◽  
Body Condition ◽  
Apparent Density ◽  
Tsetse Fly ◽  
Meat Production ◽  
Tsetse Flies ◽  
Trypanosoma Vivax ◽  
Trypanosome Species ◽  
Cross Sectional ◽  
Significant Difference

Trypanosomosis is the most serious disease of cattle, which causes great socioeconomic losses in the country. Its socioeconomic impact is reflected on direct losses due to mortality, morbidity, and reduction in milk and meat production, abortion and stillbirth, and also costs associated with combat of the disease are direct losses. A cross-sectional study was carried out to assess the prevalence of cattle trypanosomosis, and the apparent density and distribution of its fly vectors in selected study areas. The methods employed during the study were buffy coat technique for parasitological study and deploying trap for the collection of tsetse flies. A total of 1512 flies were trapped, and among them, 1162 were tsetse flies while 350 were biting flies. Higher apparent density for tsetse fly (7.7 F/T/D) followed by Stomoxys (0.9 F/T/D), Tabanus (0.8 F/T/D), and Hematopota (0.6 F/T/D) was recorded. Out of 638 examined cattle, the overall prevalence of trypanosomosis in the study area was 9.1% (58/638). Out of positive cases, Trypanosoma congolense (7.7%) was the dominant trypanosome species followed by Trypanosoma vivax (0.9%), Trypanosoma brucei (0.2%), and mixed infection of Trypanosoma brucei and Trypanosoma vivax (0.3%). There was no a significant difference (p>0.05) in trypanosome infection between age, sex, and trypanosome species. The prevalence of trypanosomosis on the bases of body condition was 2.8% for poor, 5.5% for medium, and 0.8% for good body condition. The overall prevalence of anemia was (36.8%), and presence of anemia was higher in trypanosome positive animals (62.5%) than in negative animals (34.3%) which is statistically significant (p<0.05, CI = 1.794–5.471). The overall mean packed cell volume (PCV) value for examined animals was 25.84 ± 0.252SE. Mean (PCV) of parasitaemic cattle (9.1%) was significantly (p<0.05) lower than that of aparasitaemic cattle (90%). This survey showed that trypanosomosis is still a core problem for livestock production of the study area. Therefore, more attention should be given to the control of both the disease and its vectors.

scholarly journals Developmental regulation of edited CYb and COIII mitochondrial mRNAs is achieved by distinct mechanisms in Trypanosoma brucei

2020 ◽  
Vol 48 (15) ◽  
pp. 8704-8723
Author(s):  
Joseph T Smith Jr. ◽  
Eva Doleželová ◽  
Brianna Tylec ◽  
Jonathan E Bard ◽  
Runpu Chen ◽  
...  
Keyword(s):  
Life Cycle ◽  
Trypanosoma Brucei ◽  
High Throughput Sequencing ◽  
Environmental Changes ◽  
Developmental Regulation ◽  
Complex Life Cycle ◽  
Mrna Levels ◽  
Developmentally Regulated ◽  
Life Cycle Stages

Abstract Trypanosoma brucei is a parasitic protozoan that undergoes a complex life cycle involving insect and mammalian hosts that present dramatically different nutritional environments. Mitochondrial metabolism and gene expression are highly regulated to accommodate these environmental changes, including regulation of mRNAs that require extensive uridine insertion/deletion (U-indel) editing for their maturation. Here, we use high throughput sequencing and a method for promoting life cycle changes in vitro to assess the mechanisms and timing of developmentally regulated edited mRNA expression. We show that edited CYb mRNA is downregulated in mammalian bloodstream forms (BSF) at the level of editing initiation and/or edited mRNA stability. In contrast, edited COIII mRNAs are depleted in BSF by inhibition of editing progression. We identify cell line-specific differences in the mechanisms abrogating COIII mRNA editing, including the possible utilization of terminator gRNAs that preclude the 3′ to 5′ progression of editing. By examining the developmental timing of altered mitochondrial mRNA levels, we also reveal transcript-specific developmental checkpoints in epimastigote (EMF), metacyclic (MCF), and BSF. These studies represent the first analysis of the mechanisms governing edited mRNA levels during T. brucei development and the first to interrogate U-indel editing in EMF and MCF life cycle stages.

scholarly journals RNase III Domain of KREPB9 and KREPB10 Association with Editosomes in Trypanosoma brucei

mSphere ◽  
2018 ◽  
Vol 3 (1) ◽  
Author(s):  
Jason Carnes ◽  
Suzanne M. McDermott ◽  
Kenneth Stuart
Keyword(s):  
Life Cycle ◽  
Trypanosoma Brucei ◽  
Protozoan Parasite ◽  
Tsetse Fly ◽  
Accessory Proteins ◽  
Rnase Iii ◽  
Parasite Life Cycle ◽  
Null Cell ◽  
Content Type

ABSTRACT Editosomes are the multiprotein complexes that catalyze the insertion and deletion of uridines to create translatable mRNAs in the mitochondria of kinetoplastids. Recognition and cleavage of a broad diversity of RNA substrates in vivo require three functionally distinct RNase III-type endonucleases, as well as five additional editosome proteins that contain noncatalytic RNase III domains. RNase III domains have recently been identified in the editosome accessory proteins KREPB9 and KREPB10, suggesting a role related to editing endonuclease function. In this report, we definitively show that KREPB9 and KREPB10 are not essential in either bloodstream-form parasites (BF) or procyclic-form parasites (PF) by creating null or conditional null cell lines. While preedited and edited transcripts are largely unaffected by the loss of KREPB9 in both PF and BF, loss of KREPB10 produces distinct responses in BF and PF. BF cells lacking KREPB10 also lack edited CYb, while PF cells have increased edited A6, RPS12, ND3, and COII after loss of KREPB10. We also demonstrate that mutation of the RNase III domain of either KREPB9 or KREPB10 results in decreased association with ~20S editosomes. Editosome interactions with KREPB9 and KREPB10 are therefore mediated by the noncatalytic RNase III domain, consistent with a role in endonuclease specialization in Trypanosoma brucei. IMPORTANCE Trypanosoma brucei is a protozoan parasite that causes African sleeping sickness. U insertion/deletion RNA editing in T. brucei generates mature mitochondrial mRNAs. Editing is essential for survival in mammalian hosts and tsetse fly vectors and is differentially regulated during the parasite life cycle. Three multiprotein “editosomes,” typified by exclusive RNase III endonucleases that act at distinct sites, catalyze editing. Here, we show that editosome accessory proteins KREPB9 and KREPB10 are not essential for mammalian blood- or insect-form parasite survival but have specific and differential effects on edited RNA abundance in different stages. We also characterize KREPB9 and KREPB10 noncatalytic RNase III domains and show they are essential for editosome association, potentially via dimerization with RNase III domains in other editosome proteins. This work enhances the understanding of distinct editosome and accessory protein functions, and thus differential editing, during the parasite life cycle and highlights the importance of RNase III domain interactions to editosome architecture.

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