The illustrated life cycle of Microbotryum on the host plant Silene latifolia

Botany ◽  
2010 ◽  
Vol 88 (10) ◽  
pp. 875-885 ◽  
Author(s):  
Angela Maria Schäfer ◽  
Martin Kemler ◽  
Robert Bauer ◽  
Dominik Begerow
Keyword(s):  
Life Cycle ◽  
Light And Electron Microscopy ◽  
Laboratory Data ◽  
Infection Process ◽  
Host Cells ◽  
Silene Latifolia ◽  
Long Distance ◽  
Biological Studies ◽  
Plant Parasitic

The plant-parasitic genus Microbotryum (Pucciniomycotina) has been used as a model for various biological studies, but fundamental aspects of its life history have not been documented in detail. The smut fungus is characterized by a dimorphic life cycle with a haploid saprophytic yeast-like stage and a dikaryotic plant-parasitic stage, which bears the teliospores as dispersal agents. In this study, seedlings and flowers of Silene latifolia Poir. (Caryophyllaceae) were inoculated with teliospores or sporidial cells of Microbotryum lychnidis-dioicae (DC. ex Liro) G. Deml & Oberw. and the germination of teliospores, the infection process, and the proliferation in the host tissue were documented in vivo using light and electron microscopy. Although germination of the teliospore is crucial for the establishment of Microbotryum, basidium development is variable under natural conditions. In flowers, where the amount of nutrients is thought to be high, the fungus propagates as sporidia, and mating of compatible cells takes place only when flowers are withering and nutrients are decreasing. On cotyledons (i.e., nutrient-depleted conditions), conjugation occurs shortly after teliospore germination, often via intrapromycelial mating. After formation of an infectious hypha with an appressorium, the invasion of the host occurs by direct penetration of the epidermis. While the growth in the plant is typically intercellular, long distance proliferation seems mediated through xylem tracheary elements. At the beginning of the vegetation period, fungal cells were found between meristematic shoot host cells, indicating a dormant phase inside the plant. By using different microscopy techniques, many life stages of Microbotryum are illustrated for the first time, thereby allowing new interpretations of laboratory data.

scholarly journals Organoids and Bioengineered Intestinal Models: Potential Solutions to the Cryptosporidium Culturing Dilemma

2020 ◽  
Vol 8 (5) ◽  
pp. 715 ◽  
Author(s):  
Samantha Gunasekera ◽  
Alireza Zahedi ◽  
Mark O’Dea ◽  
Brendon King ◽  
Paul Monis ◽  
...  
Keyword(s):  
Life Cycle ◽  
Host Cells ◽  
Protozoan Parasites ◽  
Future Directions ◽  
In Vivo Models ◽  
Severe Diarrhea ◽  
Transformed Cell Lines ◽  
Gnotobiotic Piglets

Cryptosporidium is a major cause of severe diarrhea-related disease in children in developing countries, but currently no vaccine or effective treatment exists for those who are most at risk of serious illness. This is partly due to the lack of in vitro culturing methods that are able to support the entire Cryptosporidium life cycle, which has led to research in Cryptosporidium biology lagging behind other protozoan parasites. In vivo models such as gnotobiotic piglets are complex, and standard in vitro culturing methods in transformed cell lines, such as HCT-8 cells, have not been able to fully support fertilization occurring in vitro. Additionally, the Cryptosporidium life cycle has also been reported to occur in the absence of host cells. Recently developed bioengineered intestinal models, however, have shown more promising results and are able to reproduce a whole cycle of infectivity in one model system. This review evaluates the recent advances in Cryptosporidium culturing techniques and proposes future directions for research that may build upon these successes.

Ultrastructure of eastern cottonwood clones susceptible or resistant to leaf rust

1987 ◽  
Vol 65 (8) ◽  
pp. 1586-1598 ◽  
Author(s):  
L. Shain ◽  
U. Järlfors
Keyword(s):  
Electron Microscopy ◽  
Leaf Rust ◽  
Light And Electron Microscopy ◽  
Infection Process ◽  
The Other ◽  
Host Cells ◽  
Eastern Cottonwood ◽  
Melampsora Medusae ◽  
Wall Appositions ◽  
Infected Cells

The infection process in four clones of eastern cottonwood susceptible or resistant to leaf rust caused by Melampsora medusae was studied by light and electron microscopy. Infection was initiated by stomatal rather than direct entry. Typical dikaryotic haustoria were observed in all clones within 1 day of inoculation. Some healthy-appearing haustoria were observed in susceptible clones throughout the duration of the study, which was terminated during the initiation of uredial production. Incompatibility was expressed differently in the two resistant clones. In clone St 75, most haustoria and invaded host cells that were observed appeared necrotic within 2 days of inoculation. Cell wall appositions appeared during this time in cells adjoining necrotic host cells. Some infected cells disintegrated within 4 days of inoculation. Affected host cells of clone St 92, on the other hand, plasmolyzed during the first 2 to 3 days after inoculation. Necrotic host cells were not observed in this clone until the 4th day after inoculation. Hyphal ramification and host plasmolysis were extensive at 6 days after inoculation.

scholarly journals In VivoLabelling of Adenovirus DNA Identifies Chromatin Anchoring and Biphasic Genome Replication

2018 ◽  
Vol 92 (18) ◽  
Author(s):  
Tetsuro Komatsu ◽  
Charlotte Quentin-Froignant ◽  
Irene Carlon-Andres ◽  
Floriane Lagadec ◽  
Fabienne Rayne ◽  
...  
Keyword(s):  
Life Cycle ◽  
Real Time ◽  
Viral Genome ◽  
Imaging System ◽  
Morphological Changes ◽  
Host Cells ◽  
Genome Replication ◽  
Equal Distribution ◽  
Viral Genomes

ABSTRACTAdenoviruses are DNA viruses with a lytic infection cycle. Following the fate of incoming as well as recently replicated genomes during infections is a challenge. In this study, we used the ANCHOR3 technology based on a bacterial partitioning system to establish a versatilein vivoimaging system for adenoviral genomes. The system allows the visualization of both individual incoming and newly replicated genomes in real time in living cells. We demonstrate that incoming adenoviral genomes are attached to condensed cellular chromatin during mitosis, facilitating the equal distribution of viral genomes in daughter cells after cell division. We show that the formation of replication centers occurs in conjunction within vivogenome replication and determine replication rates. Visualization of adenoviral DNA revealed that adenoviruses exhibit two kinetically distinct phases of genome replication. Low-level replication occurred during early replication, while high-level replication was associated with late replication phases. The transition between these phases occurred concomitantly with morphological changes of viral replication compartments and with the appearance of virus-induced postreplication (ViPR) bodies, identified by the nucleolar protein Mybbp1A. Taken together, our real-time genome imaging system revealed hitherto uncharacterized features of adenoviral genomesin vivo. The system is able to identify novel spatiotemporal aspects of the adenovirus life cycle and is potentially transferable to other viral systems with a double-stranded DNA phase.IMPORTANCEViruses must deliver their genomes to host cells to ensure replication and propagation. Characterizing the fate of viral genomes is crucial to understand the viral life cycle and the fate of virus-derived vector tools. Here, we integrated the ANCHOR3 system, anin vivoDNA-tagging technology, into the adenoviral genome for real-time genome detection. ANCHOR3 tagging permitted thein vivovisualization of incoming genomes at the onset of infection and of replicated genomes at late phases of infection. Using this system, we show viral genome attachment to condensed host chromosomes during mitosis, identifying this mechanism as a mode of cell-to-cell transfer. We characterize the spatiotemporal organization of adenovirus replication and identify two kinetically distinct phases of viral genome replication. The ANCHOR3 system is the first technique that allows the continuous visualization of adenoviral genomes during the entire virus life cycle, opening the way for further in-depth study.

scholarly journals Identification of Burkholderia pseudomallei Genes Required for the Intracellular Life Cycle and In Vivo Virulence

2006 ◽  
Vol 74 (6) ◽  
pp. 3576-3586 ◽  
Author(s):  
Sabine Pilatz ◽  
Katrin Breitbach ◽  
Nadine Hein ◽  
Beate Fehlhaber ◽  
Jessika Schulze ◽  
...  
Keyword(s):  
Life Cycle ◽  
Burkholderia Pseudomallei ◽  
Plaque Assay ◽  
Bacterial Pathogen ◽  
Hypothetical Protein ◽  
Host Cells ◽  
Growth Defect ◽  
Intracellular Growth ◽  
Endocytic Vesicles

ABSTRACT The bacterial pathogen Burkholderia pseudomallei invades host cells, escapes from endocytic vesicles, multiplies intracellularly, and induces the formation of actin tails and membrane protrusions, leading to direct cell-to-cell spreading. This study was aimed at the identification of B. pseudomallei genes responsible for the different steps of this intracellular life cycle. B. pseudomallei transposon mutants were screened for a reduced ability to form plaques on PtK2 cell monolayers as a result of reduced intercellular spreading. Nine plaque assay mutants with insertions in different open reading frames were selected for further studies. One mutant defective in a hypothetical protein encoded within the Bsa type III secretion system gene cluster was found to be unable to escape from endocytic vesicles after invasion but still multiplied within the vacuoles. Another mutant with a defect in a putative exported protein reached the cytoplasm but exhibited impaired actin tail formation in addition to a severe intracellular growth defect. In four mutants, the transposon had inserted into genes involved in either purine, histidine, or p-aminobenzoate biosynthesis, suggesting that these pathways are essential for intracellular growth. Three mutants with reduced plaque formation were shown to have gene defects in a putative cytidyltransferase, a putative lipoate-protein ligase B, and a hypothetical protein. All nine mutants proved to be significantly attenuated in a murine model of infection, with some mutants being essentially avirulent. In conclusion, we have identified a number of novel major B. pseudomallei virulence genes which are essential for the intracellular life cycle of this pathogen.

scholarly journals In vivo dynamics of active edema and lethal factors during anthrax

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Clémence Rougeaux ◽  
François Becher ◽  
Eric Ezan ◽  
Jean-Nicolas Tournier ◽  
Pierre L. Goossens
Keyword(s):  
Quantitative Methods ◽  
Protective Antigen ◽  
Lethal Factor ◽  
Infection Process ◽  
Long Distance ◽  
Infectious Process ◽  
Edema Factor ◽  
Lethal Factors ◽  
First Time

Abstract Lethal and edema toxins are critical virulence factors of Bacillus anthracis. However, little is known about their in vivo dynamics of production during anthrax. In this study, we unraveled for the first time the in vivo kinetics of production of the toxin components EF (edema factor) and LF (lethal factor) during cutaneous infection with a wild-type toxinogenic encapsulated strain in immuno-competent mice. We stratified the asynchronous infection process into defined stages through bioluminescence imaging (BLI), while exploiting sensitive quantitative methods by measuring the enzymatic activity of LF and EF. LF was produced in high amounts, while EF amounts steadily increased during the infectious process. This led to high LF/EF ratios throughout the infection, with variations between 50 to a few thousands. In the bloodstream, the early detection of active LF and EF despite the absence of bacteria suggests that they may exert long distance effects. Infection with a strain deficient in the protective antigen toxin component enabled to address its role in the diffusion of LF and EF within the host. Our data provide a picture of the in vivo complexity of the infectious process.

scholarly journals Establishment of two new myeloma cell lines from bilateral pleural effusions: evidence for sequential in vivo clonal change

Blood ◽  
1985 ◽  
Vol 66 (3) ◽  
pp. 548-555
Author(s):  
BG Durie ◽  
E Vela ◽  
V Baum ◽  
A Leibovitz ◽  
CM Payne ◽  
...  
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Chromosomal Abnormalities ◽  
Clonal Evolution ◽  
Light And Electron Microscopy ◽  
Myeloma Cell ◽  
Pleural Effusions ◽  
Probe Characteristic ◽  
Biological Studies

Two new human myeloma cell lines have been established from a 36-year- old woman with refractory IgG kappa multiple myeloma in whom bilateral malignant pleural effusions developed. The malignant plasma cells from each effusion were set up in a liquid culture using an L-15 medium containing catalase, glutathione, selenous acid, ascorbic acid, insulin, transferrin, additional glutamine hydrocortisone, and 2- mercaptoethanol and designated as M-3 medium. Two IgG kappa cell lines, LB -831 and LB-832, were established and proved to be Epstein-Barr virus negative using the internal repeat sequence DNA probe. Characteristic plasma cell morphology was evident by light and electron microscopy. Immunotyping revealed an IgG kappa , B1+, B2-, Ia (HLA- DR)+, CALLA+ phenotype for each cell line as well as for the original pleural fluid and bone marrow myeloma cells. The supernatants also contained IgG kappa, beta 2 microglobulin, and large amounts of osteoclast-activating factor (indicating bone-resorbing activity). Cytogenetic analysis of the LB-831 cell line revealed a nearly triploid highly abnormal karyotype with numerous clonal chromosomal abnormalities involving chromosomes 1, 3, 5, 7, 13, and 15; several structurally abnormal marker chromosomes; and a putative homogeneously staining region on chromosome 7p at band p22. Analysis of the LB-832 cell line revealed several additional clonal abnormalities. These additional cytogenetic changes suggest that in vivo sequential clonal evolution occurred in this patient. Therefore, two new but related cell lines have been established, which should prove useful for further biological studies.

scholarly journals In vivo structure and dynamics of the RNA genome of SARS-Cov-2

2021 ◽  
Author(s):  
Yan Zhang ◽  
Kun Huang ◽  
Dejian Xie ◽  
Jian You Lau ◽  
Wenlong Shen ◽  
...  
Keyword(s):  
Life Cycle ◽  
Structural Basis ◽  
Rna Structures ◽  
Long Distance ◽  
Alternative Structures ◽  
Translational Frameshifting ◽  
Ribosome Stalling ◽  
Positive Strand Rna ◽  
Discontinuous Transcription

AbstractThe SARS-CoV-2 coronavirus, which causes the COVID-19 pandemic, is one of the largest positive strand RNA viruses. Here we developed a simplified SPLASH assay and comprehensively mapped the in vivo RNA-RNA interactome of SARS-CoV-2 RNA during the viral life cycle. We observed canonical and alternative structures including 3’-UTR and 5’-UTR, frameshifting element (FSE) pseudoknot and genome cyclization in cells and in virions. We provide direct evidence of interactions between Transcription Regulating Sequences (TRS-L and TRS-Bs), which facilitate discontinuous transcription. In addition, we reveal alternative short and long distance arches around FSE, forming a “high-order pseudoknot” embedding FSE, which might help ribosome stalling at frameshift sites. More importantly, we found that within virions, while SARS-CoV-2 genome RNA undergoes intensive compaction, genome cyclization is weakened and genome domains remain stable. Our data provides a structural basis for the regulation of replication, discontinuous transcription and translational frameshifting, describes dynamics of RNA structures during life cycle of SARS-CoV-2, and will help to develop antiviral strategies.

scholarly journals In vivo structure and dynamics of the SARS-CoV-2 RNA genome

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yan Zhang ◽  
Kun Huang ◽  
Dejian Xie ◽  
Jian You Lau ◽  
Wenlong Shen ◽  
...  
Keyword(s):  
Life Cycle ◽  
Rna Structure ◽  
Structural Basis ◽  
Long Distance ◽  
Alternative Structures ◽  
Translational Frameshifting ◽  
Functional Relevance ◽  
Discontinuous Transcription ◽  
Whole Life Cycle

AbstractThe dynamics of SARS-CoV-2 RNA structure and their functional relevance are largely unknown. Here we develop a simplified SPLASH assay and comprehensively map the in vivo RNA-RNA interactome of SARS-CoV-2 genome across viral life cycle. We report canonical and alternative structures including 5′-UTR and 3′-UTR, frameshifting element (FSE) pseudoknot and genome cyclization in both cells and virions. We provide direct evidence of interactions between Transcription Regulating Sequences, which facilitate discontinuous transcription. In addition, we reveal alternative short and long distance arches around FSE. More importantly, we find that within virions, while SARS-CoV-2 genome RNA undergoes intensive compaction, genome domains remain stable but with strengthened demarcation of local domains and weakened global cyclization. Taken together, our analysis reveals the structural basis for the regulation of replication, discontinuous transcription and translational frameshifting, the alternative conformations and the maintenance of global genome organization during the whole life cycle of SARS-CoV-2, which we anticipate will help develop better antiviral strategies.

scholarly journals Plasmodium Falciparum Infection: In Silico Preliminary Studies

Abakós ◽  
2016 ◽  
Vol 5 (1) ◽  
pp. 63
Author(s):  
Andréia Patricia Gomes ◽  
Brenda Silveira Valles Moreira ◽  
Felipe José Dutra Dias ◽  
Victor Hiroshi Bastos Inoue ◽  
Gabriel Vita Silva Franco ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
In Silico ◽  
Ethical Issues ◽  
Plasmodium Knowlesi ◽  
Low Cost ◽  
Plasmodium Malariae ◽  
Infection Process ◽  
Host Cells

<div class="page" title="Page 3"><div class="layoutArea"><div class="column"><p><span>Malaria is an infectious disease of great impact in terms of public health, given the number of people affected and subjected to the risk of illness. Protozoa of the genus Plasmodium cause it and five species can infect humans: </span><em>Plasmodium falciparum</em><span>, </span><em>Plasmodium vivax</em><span>, </span><em>Plasmodium ovale</em><span>, </span><em>Plasmodium malariae </em><span>and </span><em>Plasmodium knowlesi</em><span>; the first is able to produce the most severe cases of the disease. Despite its clinical and epidemiological relevance and investigations in development – targeted at different aspects of the interaction between humans and </span><em>Plasmodium </em><span>protozoa of the genus – there remains many questions about different aspects of the malaria pathophysiology. To study such gaps, interdisciplinary strategies can be pursed, which involve biology, medicine an computer science, as part of the trial </span><span>in silico</span><span>. Such approach provides agility, low cost and does not imply ethical issues that permeate the experiments </span><em>in vitro </em><span>and </span><em>in vivo</em><span>. Based on these considerations, this article presents preliminary results of a computational model of the interaction between </span><em>P. falciparum </em><span>and erythrocytes, implemented in </span><em>AutoSimmune </em><span>system. The results obtained show that the system is able to simulate the host cells infection process by protozoan with similarities with the biological reality. </span></p></div></div></div>

scholarly journals In Vitro and In Vivo Characterization of a Bordetella bronchiseptica Mutant Strain with a Deep Rough Lipopolysaccharide Structure

2002 ◽  
Vol 70 (4) ◽  
pp. 1791-1798 ◽  
Author(s):  
Federico Sisti ◽  
Julieta Fernández ◽  
María Eugenia Rodríguez ◽  
Antonio Lagares ◽  
Nicole Guiso ◽  
...  
Keyword(s):  
Parental Strain ◽  
Infection Process ◽  
Bordetella Bronchiseptica ◽  
Host Cells ◽  
Virulence Determinants ◽  
Chronic Infections ◽  
In Vivo Experiments ◽  
Dominant Phenotype

ABSTRACT Bordetella bronchiseptica is closely related to Bordetella pertussis, which produces respiratory disease primarily in mammals other than humans. However, its importance as a human pathogen is being increasingly recognized. Although a large amount of research on Bordetella has been generated regarding protein virulence factors, the participation of the surface lipopolysaccharide (LPS) during B. bronchiseptica infection is less understood. To get a better insight into this matter, we constructed and characterized the behavior of an LPS mutant with the deepest possible rough phenotype. We generated the defective mutant B. bronchiseptica LP39 on the waaC gene, which codes for a heptosyl transferase involved in the biosynthesis of the core region of the LPS molecule. Although in B. bronchiseptica LP39 the production of the principal virulence determinants adenylate cyclase-hemolysin, filamentous hemagglutinin, and pertactin persisted, the quantity of the two latter factors was diminished, with the levels of pertactin being the most greatly affected. Furthermore, the LPS of B. bronchiseptica LP39 did not react with sera obtained from mice that had been infected with the parental strain, indicating that this defective LPS is immunologically different from the wild-type LPS. In vivo experiments demonstrated that the ability to colonize the respiratory tract is reduced in the mutant, being effectively cleared from lungs within 5 days, whereas the parental strain survived at least for 30 days. In vitro experiments have demonstrated that, although B. bronchiseptica LP39 was impaired for adhesion to human epithelial cells, it is still able to survive within the host cells as efficiently as the parental strain. These results seem to indicate that the deep rough form of B. bronchiseptica LPS cannot represent a dominant phenotype at the first stage of colonization. Since isolates with deep rough LPS phenotype have already been obtained from human B. bronchiseptica chronic infections, the possibility that this phenotype arises as a consequence of selection pressure within the host at a late stage of the infection process is discussed.

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