scholarly journals The Life Cycle of Toxoplasma gondii in the Natural Environment

10.5772/48233 ◽  
2012 ◽  
Author(s):  
Emmanuelle Gilot-Fromont ◽  
Maud Llu ◽  
Marie-Laure Dard ◽  
Cline Richomme ◽  
Dominique Aubert ◽  
...  
Keyword(s):  
Life Cycle ◽  
Toxoplasma Gondii ◽  
Natural Environment

The Rise of “Environmental Sustainability Knowledge” in Business Strategy and Entrepreneurship

2014 ◽  
pp. 221-238
Author(s):  
Jean Marie Ip-Soo-Ching ◽  
Suzanne Zyngier
Keyword(s):  
Information Technology ◽  
Life Cycle ◽  
Conceptual Framework ◽  
Natural Environment ◽  
Environmental Sustainability ◽  
Business Strategy ◽  
Local Community ◽  
Community Education ◽  
Business Sustainability ◽  
Knowledge Based

This chapter articulates a conceptual framework to analyse the management of environmental sustainability knowledge in tourism that is underpinned by both the knowledge-based view of the firm (Grant, 1996; Spender, 1996) and the KM Life Cycle (Liebowitz & Beckman, 1998; Salisbury, 2012). This deliberate management of knowledge enables NTOs to build a knowledge-base about the natural environment and to use that knowledge for environmental sustainability, business sustainability, and local community education. Ten NTOs in Australia, Malaysia, Thailand, and Vietnam were investigated to analyse their KM of environmental sustainability. In supporting the knowledge-based view and KM of environmental sustainability knowledge, a further conceptual framework is also advanced for the analysis of how Information Technology enables environmental sustainability knowledge to be created, captured, shared, and applied at NTOs among their staff, customers, and communities.

scholarly journals Identification of Fis1 Interactors in Toxoplasma gondii Reveals a Novel Protein Required for Peripheral Distribution of the Mitochondrion

mBio ◽  
2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Kylie Jacobs ◽  
Robert Charvat ◽  
Gustavo Arrizabalaga
Keyword(s):  
Life Cycle ◽  
Toxoplasma Gondii ◽  
Morphological Changes ◽  
Dominant Negative Effect ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Morphology ◽  
Content Type ◽  
Membrane Contact Sites ◽  
Intracellular Parasites ◽  
Single Mitochondrion

ABSTRACT Toxoplasma gondii’s single mitochondrion is very dynamic and undergoes morphological changes throughout the parasite’s life cycle. During parasite division, the mitochondrion elongates, enters the daughter cells just prior to cytokinesis, and undergoes fission. Extensive morphological changes also occur as the parasite transitions from the intracellular environment to the extracellular environment. We show that treatment with the ionophore monensin causes reversible constriction of the mitochondrial outer membrane and that this effect depends on the function of the fission-related protein Fis1. We also observed that mislocalization of the endogenous Fis1 causes a dominant-negative effect that affects the morphology of the mitochondrion. As this suggests that Fis1 interacts with proteins critical for maintenance of mitochondrial structure, we performed various protein interaction trap screens. In this manner, we identified a novel outer mitochondrial membrane protein, LMF1, which is essential for positioning of the mitochondrion in intracellular parasites. Normally, while inside a host cell, the parasite mitochondrion is maintained in a lasso shape that stretches around the parasite periphery where it has regions of coupling with the parasite pellicle, suggesting the presence of membrane contact sites. In intracellular parasites lacking LMF1, the mitochondrion is retracted away from the pellicle and instead is collapsed, as normally seen only in extracellular parasites. We show that this phenotype is associated with defects in parasite fitness and mitochondrial segregation. Thus, LMF1 is necessary for mitochondrial association with the parasite pellicle during intracellular growth, and proper mitochondrial morphology is a prerequisite for mitochondrial division. IMPORTANCE Toxoplasma gondii is an opportunistic pathogen that can cause devastating tissue damage in the immunocompromised and congenitally infected. Current therapies are not effective against all life stages of the parasite, and many cause toxic effects. The single mitochondrion of this parasite is a validated drug target, and it changes its shape throughout its life cycle. When the parasite is inside a cell, the mitochondrion adopts a lasso shape that lies in close proximity to the pellicle. The functional significance of this morphology is not understood and the proteins involved are currently not known. We have identified a protein that is required for proper mitochondrial positioning at the periphery and that likely plays a role in tethering this organelle. Loss of this protein results in dramatic changes to the mitochondrial morphology and significant parasite division and propagation defects. Our results give important insight into the molecular mechanisms regulating mitochondrial morphology.

scholarly journals A Comparison of Stage Conversion in the Coccidian Apicomplexans Toxoplasma gondii, Hammondia hammondi, and Neospora caninum

2020 ◽  
Vol 10 ◽  
Author(s):  
Sarah L. Sokol-Borrelli ◽  
Rachel S. Coombs ◽  
Jon P. Boyle
Keyword(s):  
Life Cycle ◽  
Toxoplasma Gondii ◽  
Stress Responses ◽  
Neospora Caninum ◽  
Life Forms ◽  
New Host ◽  
Environmental Signals ◽  
Stage Conversion ◽  
Genetic Components ◽  
Species Specific

Stage conversion is a critical life cycle feature for several Apicomplexan parasites as the ability to switch between life forms is critical for replication, dissemination, pathogenesis and ultimately, transmission to a new host. In order for these developmental transitions to occur, the parasite must first sense changes in their environment, such as the presence of stressors or other environmental signals, and then respond to these signals by initiating global alterations in gene expression. As our understanding of the genetic components required for stage conversion continues to broaden, we can better understand the conserved mechanisms for this process and unique components and their contribution to pathogenesis by comparing stage conversion in multiple closely related species. In this review, we will discuss what is currently known about the mechanisms driving stage conversion in Toxoplasma gondii and its closest relatives Hammondia hammondi and Neospora caninum. Work by us and others has shown that these species have some important differences in the way that they (1) progress through their life cycle and (2) respond to stage conversion initiating stressors. To provide a specific example of species-specific complexities associated with stage conversion, we will discuss our recent published and unpublished work comparing stress responses in T. gondii and H. hammondi.

Intermediate and paratenic hosts in the life cycle of Aelurostrongylus abstrusus in natural environment

2013 ◽  
Vol 198 (3-4) ◽  
pp. 401-405 ◽  
Author(s):  
Witold Jeżewski ◽  
Katarzyna Buńkowska-Gawlik ◽  
Joanna Hildebrand ◽  
Agnieszka Perec-Matysiak ◽  
Zdzisław Laskowski
Keyword(s):  
Life Cycle ◽  
Natural Environment ◽  
Aelurostrongylus Abstrusus ◽  
Paratenic Hosts

Mathematical Modeling of Within-Host Dynamics of Toxoplasma Gondii

2011 ◽  
Author(s):  
Adam Sullivan ◽  
Xiaopeng Zhao ◽  
Chunlei Su
Keyword(s):  
Life Cycle ◽  
Toxoplasma Gondii ◽  
Cellular Automata ◽  
Three Dimensional ◽  
Host Cells ◽  
Time Step ◽  
Cellular Automata Model ◽  
Entire Life ◽  
Entire Life Cycle ◽  
The Brain

Toxoplasma gondii is a protozoan capable of replicating sexually in cats and asexually in other warm-blooded animals. By using a three dimensional mesh of both the brain and spleen, it is possible to simulate using a computational model to demonstrate the entire life-cycle within an intermediate host of the parasite as it completes the life-cycle using host cells of these organs. A cellular automata model is developed to demonstrate the dynamics of the parasite, where each cell follows the same set of rules for each discrete time-step. This cellular automata model allows for data simulations to be run of the parasite within a mouse and display graphical images and animations.

scholarly journals Life cycle of toxoplasma gondii.

BMJ ◽  
1969 ◽  
Vol 4 (5686) ◽  
pp. 806-806 ◽  
Author(s):  
W M Hutchison ◽  
J F Dunachie ◽  
J C Siim ◽  
K Work
Keyword(s):  
Life Cycle ◽  
Toxoplasma Gondii

Lack of seasonal variation in the life-history strategies of the trematode Coitocaecum parvum: no apparent environmental effect

Parasitology ◽  
2008 ◽  
Vol 135 (10) ◽  
pp. 1243-1251 ◽  
Author(s):  
C. LAGRUE ◽  
R. POULIN
Keyword(s):  
Life History ◽  
Seasonal Variation ◽  
Life Cycle ◽  
Water Temperature ◽  
Intermediate Host ◽  
Definitive Host ◽  
Natural Environment ◽  
Life History Strategy ◽  
Life Cycles ◽  
Coitocaecum Parvum

SUMMARYParasites with complex life cycles have developed numerous and very diverse adaptations to increase the likelihood of completing this cycle. For example, some parasites can abbreviate their life cycles by skipping the definitive host and reproducing inside their intermediate host. The resulting shorter life cycle is clearly advantageous when definitive hosts are absent or rare. In species where life-cycle abbreviation is facultative, this strategy should be adopted in response to seasonally variable environmental conditions. The hermaphroditic trematode Coitocaecum parvum is able to mature precociously (progenesis), and produce eggs by selfing while still inside its amphipod second intermediate host. Several environmental factors such as fish definitive host density and water temperature are known to influence the life-history strategy adopted by laboratory raised C. parvum. Here we document the seasonal variation of environmental parameters and its association with the proportion of progenetic individuals in a parasite population in its natural environment. We found obvious seasonal patterns in both water temperature and C. parvum host densities. However, despite being temporally variable, the proportion of progenetic C. parvum individuals was not correlated with any single parameter. The results show that C. parvum life-history strategy is not as flexible as previously thought. It is possible that the parasite's natural environment contains so many layers of heterogeneity that C. parvum does not possess the ability to adjust its life-history strategy to accurately match the current conditions.

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