scholarly journals Hurricane Juan (2003). Part I: A Diagnostic and Compositing Life Cycle Study

2006 ◽  
Vol 134 (7) ◽  
pp. 1725-1747 ◽  
Author(s):  
Ron McTaggart-Cowan ◽  
Eyad H. Atallah ◽  
John R. Gyakum ◽  
Lance F. Bosart
Keyword(s):  
Life Cycle ◽  
East Coast ◽  
Leading Edge ◽  
High Amplitude ◽  
Complex Life Cycle ◽  
Low Latitude ◽  
Initial Development ◽  
Easterly Wave ◽  
Case Diagnosis

Abstract A detailed analysis of the complex life cycle of Hurricane Juan (in 2003) is undertaken to elucidate the structures and forcings that prevailed over the period leading up to the hurricane’s landfall in Halifax, Nova Scotia, Canada. Despite the presence of easterly wave precursors, Hurricane Juan’s initial development is shown to occur in a baroclinic environment beneath a low-latitude potential vorticity streamer. This feature interacts with a lower-level shear line as the incipient vortex begins to effectively focus ascent and convection. The system undergoes a slow tropical transition over a period of several days as the deep-layer shear over the developing storm decreases. The hurricane is repeatedly perturbed by subsynoptic-scale waves traveling along the leading edge of a large upstream trough. However, Hurricane Juan maintains its tropical structure despite its relatively high formation latitude (28°N) and its northward trajectory. The unusual persistence of the storm’s tropical nature as it propagates northward is of primary interest in this study. In particular, the role of persistent ridging along the east coast of North America is investigated both in high-resolution analyses for Hurricane Juan and in a compositing framework. Dynamic tropopause, quasigeostrophic, and modified Eady model diagnostics are used to elucidate the interactions between Hurricane Juan and this amplified midlatitude flow. Given the strength and persistence of the anomalous ridge–trough couplet both in the case diagnosis and in the composite fields, the study concludes that the presence of prestorm, high-amplitude ridging along the east coast likely reinforced by diabatic ridging downshear of the storm itself produces an environment both dynamically and thermodynamically conducive to the high-latitude landfall of hurricanes still in the tropical phase.

scholarly journals Role of two metacaspases in development and pathogenicity of the Rice Blast fungus, Magnaporthe oryzae

2020 ◽  
Author(s):  
Jessie Fernandez ◽  
Victor Lopez ◽  
Lisa Kinch ◽  
Mariel A. Pfeifer ◽  
Hillery Gray ◽  
...  
Keyword(s):  
Cell Death ◽  
Food Security ◽  
Life Cycle ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Rice Blast Disease ◽  
Blast Disease ◽  
Complex Life Cycle ◽  
Insight Into

ABSTRACTRice blast disease caused by Magnaporthe oryzae is a devastating disease of cultivated rice worldwide. Infections by this fungus lead to a significant reduction in rice yields and threats to food security. To gain better insight into growth and cell death in M. oryzae during infection, we characterized two predicted M. oryzae metacaspase proteins, MoMca1 and MoMca2. These proteins appear to be functionally redundant and are able to complement the yeast Yca1 homologue. Biochemical analysis revealed that M. oryzae metacaspases exhibited Ca2+ dependent caspase activity in vitro. Deletion of both MoMca1 and MoMca2 in M. oryzae resulted in reduced sporulation, delay in conidial germination and attenuation of disease severity. In addition, the double ΔMomca1mca2 mutant strain showed increased radial growth in the presence of oxidative stress. Interestingly, the ΔMomca1mca2 strain showed an increase accumulation of insoluble aggregates compared to the wild-type strain during vegetative growth. Our findings suggest that MoMca1 and MoMca2 promote the clearance of insoluble aggregates in M. oryzae, demonstrating the important role these metacaspases have in fungal protein homeostasis. Furthermore, these metacaspase proteins may play additional roles, like in regulating stress responses, that would help maintain the fitness of fungal cells required for host infection.IMPORTANCEMagnaporthe oryzae causes rice blast disease that threatens global food security by resulting in the severe loss of rice production every year. A tightly regulated life cycle allows M. oryzae to disarm the host plant immune system during its biotrophic stage before triggering plant cell death in its necrotrophic stage. The ways M. oryzae navigates its complex life cycle remains unclear. This work characterizes two metacaspase proteins with peptidase activity in M. oryzae that are shown to be involved in the regulation of fungal growth and development prior to infection by potentially helping maintain fungal fitness. This study provides new insight into the role of metacaspase proteins in filamentous fungi by illustrating the delays in M. oryzae morphogenesis in the absence of these proteins. Understanding the mechanisms by which M. oryzae morphology and development promote its devastating pathogenicity may lead to the emergence of proper methods for disease control.

scholarly journals Metamorphoses of malaria: the role of autophagy in parasite differentiation

2011 ◽  
Vol 51 ◽  
pp. 127-136 ◽  
Author(s):  
Isabelle Coppens
Keyword(s):  
Life Cycle ◽  
Complex Life Cycle ◽  
Mammalian Host ◽  
Protozoan Parasites ◽  
Membrane Complex ◽  
Autophagic Process ◽  
Inner Membrane Complex ◽  
Form Development ◽  
High Degree

Several protozoan parasites undergo a complex life cycle that alternates between an invertebrate vector and a vertebrate host. Adaptations to these different environments by the parasites are achieved by drastic changes in their morphology and metabolism. The malaria parasites must be transmitted to a mammal from a mosquito as part of their life cycle. Upon entering the mammalian host, extracellular malaria sporozoites reach the liver and invade hepatocytes, wherein they meet the challenge of becoming replication-competent schizonts. During the process of conversion, the sporozoite selectively discards organelles that are unnecessary for the parasite growth in liver cells. Among the organelles that are cleared from the sporozoite are the micronemes, abundant secretory vesicles that facilitate the adhesion of the parasite to hepatocytes. Organelles specialized in sporozoite motility and structure, such as the inner membrane complex (a major component of the motile parasite's cytoskeleton), are also eliminated from converting parasites. The high degree of sophistication of the metamorphosis that occurs at the onset of the liver-form development cascade suggests that the observed changes must be multifactorial. Among the mechanisms implicated in the elimination of sporozoite organelles, the degradative process called autophagy contributes to the remodelling of the parasite interior and the production of replicative liver forms. In a broader context, the importance of the role played by autophagy during the differentiation of protozoan parasites that cycle between insects and vertebrates is nowadays clearly emerging. An exciting prospect derived from these observations is that the parasite proteins involved in the autophagic process may represent new targets for drug development.

scholarly journals Role of Two Metacaspases in Development and Pathogenicity of the Rice Blast Fungus Magnaporthe oryzae

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jessie Fernandez ◽  
Victor Lopez ◽  
Lisa Kinch ◽  
Mariel A. Pfeifer ◽  
Hillery Gray ◽  
...  
Keyword(s):  
Cell Death ◽  
Food Security ◽  
Life Cycle ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Rice Blast Disease ◽  
Blast Disease ◽  
Complex Life Cycle ◽  
Content Type

ABSTRACT Rice blast disease caused by Magnaporthe oryzae is a devastating disease of cultivated rice worldwide. Infections by this fungus lead to a significant reduction in rice yields and threats to food security. To gain better insight into growth and cell death in M. oryzae during infection, we characterized two predicted M. oryzae metacaspase proteins, MoMca1 and MoMca2. These proteins appear to be functionally redundant and can complement the yeast Yca1 homologue. Biochemical analysis revealed that M. oryzae metacaspases exhibited Ca2+-dependent caspase activity in vitro. Deletion of both MoMca1 and MoMca2 in M. oryzae resulted in reduced sporulation, delay in conidial germination, and attenuation of disease severity. In addition, the double ΔMomca1mca2 mutant strain showed increased radial growth in the presence of oxidative stress. Interestingly, the ΔMomca1mca2 strain showed an increased accumulation of insoluble aggregates compared to the wild-type strain during vegetative growth. Our findings suggest that MoMca1 and MoMca2 promote the clearance of insoluble aggregates in M. oryzae, demonstrating the important role these metacaspases have in fungal protein homeostasis. Furthermore, these metacaspase proteins may play additional roles, like in regulating stress responses, that would help maintain the fitness of fungal cells required for host infection. IMPORTANCE Magnaporthe oryzae causes rice blast disease that threatens global food security by resulting in the severe loss of rice production every year. A tightly regulated life cycle allows M. oryzae to disarm the host plant immune system during its biotrophic stage before triggering plant cell death in its necrotrophic stage. The ways M. oryzae navigates its complex life cycle remain unclear. This work characterizes two metacaspase proteins with peptidase activity in M. oryzae that are shown to be involved in the regulation of fungal growth and development prior to infection by potentially helping maintain fungal fitness. This study provides new insights into the role of metacaspase proteins in filamentous fungi by illustrating the delays in M. oryzae morphogenesis in the absence of these proteins. Understanding the mechanisms by which M. oryzae morphology and development promote its devastating pathogenicity may lead to the emergence of proper methods for disease control.

scholarly journals Glutamine Analogues Impair Cell Proliferation, the Intracellular Cycle and Metacyclogenesis in Trypanosoma cruzi

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1628
Author(s):  
Rodolpho Ornitz Oliveira Souza ◽  
Marcell Crispim ◽  
Ariel Mariano Silber ◽  
Flávia Silva Damasceno
Keyword(s):  
Cell Proliferation ◽  
Life Cycle ◽  
Trypanosoma Cruzi ◽  
Host Cells ◽  
Glutamine Metabolism ◽  
Complex Life Cycle ◽  
Mammalian Host ◽  
Developmental Cycle ◽  
Parasite Life Cycle

Trypanosoma cruzi is the aetiologic agent of Chagas disease, which affects people in the Americas and worldwide. The parasite has a complex life cycle that alternates among mammalian hosts and insect vectors. During its life cycle, T. cruzi passes through different environments and faces nutrient shortages. It has been established that amino acids, such as proline, histidine, alanine, and glutamate, are crucial to T. cruzi survival. Recently, we described that T. cruzi can biosynthesize glutamine from glutamate and/or obtain it from the extracellular environment, and the role of glutamine in energetic metabolism and metacyclogenesis was demonstrated. In this study, we analysed the effect of glutamine analogues on the parasite life cycle. Here, we show that glutamine analogues impair cell proliferation, the developmental cycle during the infection of mammalian host cells and metacyclogenesis. Taken together, these results show that glutamine is an important metabolite for T. cruzi survival and suggest that glutamine analogues can be used as scaffolds for the development of new trypanocidal drugs. These data also reinforce the supposition that glutamine metabolism is an unexplored possible therapeutic target.

scholarly journals Functional Diversity of the Schistosoma mansoni Tyrosine Kinases

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Lívia G. A. Avelar ◽  
Laila A. Nahum ◽  
Luiza F. Andrade ◽  
Guilherme Oliveira
Keyword(s):  
Life Cycle ◽  
Schistosoma Mansoni ◽  
Tyrosine Kinases ◽  
Large Body ◽  
Protein Domain ◽  
Complex Life Cycle ◽  
Main Process ◽  
Parasite Life Cycle ◽  
Causative Agents

Schistosoma mansoni, one of the causative agents of schistosomiasis, has a complex life cycle infecting over 200 million people worldwide. Such a successful and prolific parasite life cycle has been shown to be dependent on the adaptive interaction between the parasite and hosts. Tyrosine kinases (TKs) play a key role in signaling pathways as demonstrated by a large body of experimental work in eukaryotes. Furthermore, comparative genomics have allowed the identification of TK homologs and provided insights into the functional role of TKs in several biological systems. Finally, TK structural biology has provided a rational basis for obtaining selective inhibitors directed to the treatment of human diseases. This paper covers the important aspects of the phospho-tyrosine signaling network in S. mansoni, Caenorhabditis elegans, and humans, the main process of functional diversification of TKs, that is, protein-domain shuffling, and also discusses TKs as targets for the development of new anti-schistosome drugs.

scholarly journals Expression and Physiological Role of Three Myxococcus xanthus Copper-Dependent P1B-Type ATPases during Bacterial Growth and Development

2010 ◽  
Vol 76 (18) ◽  
pp. 6077-6084 ◽  
Author(s):  
Aurelio Moraleda-Muñoz ◽  
Juana Pérez ◽  
Antonio Luis Extremera ◽  
José Muñoz-Dorado
Keyword(s):  
Life Cycle ◽  
Expression Profiles ◽  
Myxococcus Xanthus ◽  
Physiological Role ◽  
Copper Homeostasis ◽  
Cellular Damage ◽  
Complex Life Cycle ◽  
Sequence Motifs ◽  
Dual Effect

ABSTRACT Myxococcus xanthus is a soil-dwelling bacterium that exhibits a complex life cycle comprising social behavior, morphogenesis, and differentiation. In order to successfully complete this life cycle, cells have to cope with changes in their environment, among which the presence of copper is remarkable. Copper is an essential transition metal for life, but an excess of copper provokes cellular damage by oxidative stress. This dual effect forces the cells to maintain a tight homeostasis. M. xanthus encodes a large number of genes with similarities to others reported previously to be involved in copper homeostasis, most of which are redundant. We have identified three genes that encode copper-translocating P1B-ATPases (designated copA, copB, and copC) that exhibit the sequence motifs and modular organizations of those that extrude Cu+. The expression of the ATPase copC has not been detected, but copA and copB are differentially regulated by the addition of external copper. However, while copB expression peaks at 2 h, copA is expressed at higher levels, and the maximum is reached much later. The fact that these expression profiles are nearly identical to those exhibited by the multicopper oxidases cuoA and cuoB suggests that the pairs CuoB-CopB and CuoA-CopA sequentially function to detoxify the cell. The deletion of any ATPase alters the expression profiles of other genes involved in copper homeostasis, such as the remaining ATPases or the Cus systems, yielding cells that are more resistant to the metal.

The Role of Convectively Coupled Atmospheric Kelvin Waves on African Easterly Wave Activity

2013 ◽  
Vol 141 (6) ◽  
pp. 1910-1924 ◽  
Author(s):  
Michael J. Ventrice ◽  
Chris D. Thorncroft
Keyword(s):  
Vertical Wind Shear ◽  
Leading Edge ◽  
Active Phase ◽  
Kelvin Waves ◽  
Boreal Summer ◽  
African Easterly Jet ◽  
African Easterly Wave ◽  
Easterly Wave ◽  
West African Coast

Abstract The role of convectively coupled atmospheric Kelvin waves (CCKWs) on African easterly wave (AEW) activity is explored over tropical Africa during boreal summer. Examination of the pre-Alberto AEW in 2000 highlights the observation that the convective trigger for the initiation of the AEW was generated by a strong CCKW and that the subsequent intensification of the AEW at the West African coast was associated with a second CCKW. Composite analysis shows that, generally, AEW activity increases during and after the passage of the convectively active phase of strong CCKWs. The increase in AEW activity is consistent with convective triggering at the leading edge of the convective phase of the CCKW. This convective triggering occurs in a region where the background low-level easterly vertical wind shear is increased by the CCKW. As the AEW propagates westward through the convectively active phase of the CCKW, it can develop in an environment favorable for convection. It is also shown that this phase of the CCKW is characterized by enhanced meridional vorticity gradients in the core of the African easterly jet suggesting that enhanced mixed barotropic–baroclinic growth may also be responsible for enhanced AEW activity there.

scholarly journals Transcriptomic changes across the life cycle of Trypanosoma cruzi II

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8947 ◽  
Author(s):  
Lissa Cruz-Saavedra ◽  
Gustavo A. Vallejo ◽  
Felipe Guhl ◽  
Juan David Ramírez
Keyword(s):  
Life Cycle ◽  
Trypanosoma Cruzi ◽  
Signaling Pathway ◽  
Complex Life Cycle ◽  
Gene Expressions ◽  
Rna Regulation ◽  
Pathway Reconstruction ◽  
Transcriptomic Changes ◽  
Metacyclic Trypomastigote

Trypanosoma cruzi is a flagellated protozoan that causes Chagas disease; it presents a complex life cycle comprising four morphological stages: epimastigote (EP), metacyclic trypomastigote (MT), cell-derived trypomastigote (CDT) and amastigote (AM). Previous transcriptomic studies on three stages (EPs, CDTs and AMs) have demonstrated differences in gene expressions among them; however, to the best of our knowledge, no studies have reported on gene expressions in MTs. Therefore, the present study compared differentially expressed genes (DEGs), and signaling pathway reconstruction in EPs, MTs, AMs and CDTs. The results revealed differences in gene expressions in the stages evaluated; these differences were greater between MTs and AMs-PTs. The signaling pathway that presented the highest number of DEGs in all the stages was associated with ribosomes protein profiles, whereas the other related pathways activated were processes related to energy metabolism from glucose, amino acid metabolism, or RNA regulation. However, the role of autophagy in the entire life cycle of T. cruzi and the presence of processes such as meiosis and homologous recombination in MTs (where the expressions of SPO11 and Rad51 plays a role) are crucial. These findings represent an important step towards the full understanding of the molecular basis during the life cycle of T. cruzi.

scholarly journals Do cave orb spiders show unique behavioural adaptations to subterranean life? A review of the evidence

Behaviour ◽  
2019 ◽  
Vol 156 (10) ◽  
pp. 969-996 ◽  
Author(s):  
Thomas Hesselberg ◽  
Daniel Simonsen ◽  
Carlos Juan
Keyword(s):  
Life Cycle ◽  
Life Stage ◽  
Current Data ◽  
Complex Life Cycle ◽  
Model Organisms ◽  
Surface Phase ◽  
Cave Environment ◽  
Surface Dwelling ◽  
Behavioural Adaptations

Abstract Interest for subterranean biology has risen sharply in recent years due to the simplicity of the cave environment. However, most studies have focussed on morphology with few studies looking at behaviour. The cave orb spiders show some unique behavioural adaptations compared to other orb spiders, including rudimentary orb webs, off-web foraging and a complex life cycle with a surface phase. Here, we compare these behavioural adaptations in the European Meta menardi and Meta bourneti to similar behaviours in surface-dwelling orb spiders. We find that current data suggest (1) an extreme reduction in the number of frame threads, (2) evidence of capturing non-flying prey, but not necessarily evidence for off-web foraging and (3) dispersal through a surface-dwelling life stage, but with data lacking on the role of ballooning and their return to caves. We conclude that Meta spiders have potential as model organisms for studies on behavioural adaptations and flexibility.

Schistosoma mansoni male–female interactions

2004 ◽  
Vol 82 (2) ◽  
pp. 357-374 ◽  
Author(s):  
Philip T LoVerde ◽  
Edward G Niles ◽  
Ahmed Osman ◽  
Wenjie Wu
Keyword(s):  
Life Cycle ◽  
Schistosoma Mansoni ◽  
Egg Production ◽  
Reproductive Development ◽  
Host Factors ◽  
Complex Life Cycle ◽  
Morphological Observation ◽  
Male Worm ◽  
Male And Female

Schistosome parasites are muticellular eucaryotic organisms with a complex life cycle that involves mammalian and snail hosts. Unlike other trematode parasites, schistosomes (along with the Didymozoidae) have evolved separate sexes or dioecy. Sex is determined by a chromosomal mechanism. The dioecious state created an opportunity for the sexes to play a role in schistosome evolution that has resulted in an interesting interplay between the sexes. The classical observation, made more than 50 years ago, is that female schistosomes do not develop unless a male worm is present. Studies up through the 1990s focused on dissecting the role of the sexes in mate attraction, mate choice, mating behavior, female growth, female reproductive development, egg production, and other sex-evolved functions. In the mid-1980s, studies began to address the molecular events of male–female interactions. The classic morphological observation that female schistosomes do not complete reproductive development unless a male worm is present has been redefined in molecular terms. The male by an unknown mechanism transduces a signal that regulates female gene expression in a stage-, tissue-, and temporal-specific manner. A number of female-specific genes have been identified, along with signaling pathways and nuclear receptors, that play a role in female reproductive development. In addition, a number of host factors such as cytokines have also been demonstrated to affect adult male and female development and egg production. This review focuses on the biological interactions of the male and female schistosome and the role of parasite and host factors in these interactions as they contribute to the life cycle of Schistosoma mansoni.

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