scholarly journals Critical aspects of phytoalexins in potato

1987 ◽  
Vol 59 (3) ◽  
pp. 217-230
Author(s):  
Sture Brishammer
Keyword(s):  
Host Cells ◽  
Potato Tubers ◽  
Inhibitory Effects ◽  
Host Parasite Interactions ◽  
Different Types ◽  
Endogenous Elicitor ◽  
Artificial Inoculations ◽  
Host Parasite ◽  
Critical Aspects

Phytoalexins in potato are sesquiterpenoid substances produced in response to infections and are believed to help plants resist attack by pathogens. However, these compounds appear in response to compatible as well as incompatible interactions and only accumulate in the tubers. The amounts of phytoalexins produced depend on the physiological condition of the tubers. Young tubers don’t get easily infected with Phytophthora infestans even though they synthesize extremely small amounts of phytoalexins. Furthermore, confusion as to the identity of specific races and the propensity for a given race to produce different effects in the same type of host makes it extremely difficult to predict host-parasite interactions with any acceptable degree of accuracy. It is doubtful that the production of phytoalexins in response to artificial inoculations is representative of that occurring in natural infections. Markedly different types of pathogens induce synthesis of same substances in the host cells. It therefore seems most probable that all the phytoalexins are synthesized in response to stimulation by an endogenous elicitor. Little knowledge is available regarding the biosynthesis of these sesquiterpenes, and many previous determinations have presumably been erroneous. When potato tubers were inoculated with the late blight fungus, secondarily appearing bacteria were not retarded, despite the presence of phytoalexins. There is no generally accepted hypothesis describing the mechanism by which phytoalexins inhibit pathogens and no distinction has been made between the effects on necrotrophs and biotrophs. Adequate bioassays capable of measuring the effects of inhibition have yet to be developed, thus far, no convincing inhibitory effects have been reported. During purification of the phytoalexins there is a high risk for artifact forming, implying that specific compounds cannot be detected with certainty. Moreover, present analytical methods must be improved before we can determine how phytoalexins act in vivo. Probably, phytoalexins are synthesized at a stage in the infection too late to be able to restrict its expansion with the tissues of the host. Phytoalexins are restricted to the attacked parts of the tubers and there is no evidence indicating that these compounds pose any health risks when present in potatoes used for consumption.

scholarly journals Transmigration of Trypanosoma cruzi trypomastigotes through 3D cultures resembling a physiological environment

2019 ◽  
Author(s):  
Matías Exequiel Rodríguez ◽  
Mariana Rizzi ◽  
Lucas D. Caeiro ◽  
Yamil E. Masip ◽  
Alina Perrone ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Three Dimensional ◽  
3D Cultures ◽  
Monolayer Cultures ◽  
Host Parasite Interactions ◽  
Virulent Strains ◽  
Host Parasite ◽  
3D Spheroids

AbstractChaga’ disease, caused by the kinetoplastid parasite Trypanosoma cruzi, presents a variety of chronic clinical manifestations whose determinants are still unknown but probably influenced by the host-parasite interplay established during the first stages of the infection, when bloodstream circulating trypomastigotes disseminate to different organs and tissues. After leaving the blood, trypomastigotes must migrate through tissues to invade cells and establish a chronic infection. How this process occurs remains unexplored. Three-dimensional (3D) cultures are physiologically relevant because mimic the microarchitecture of tissues and provide an environment similar to the encountered in natural infections. In this work, we combined the 3D culture technology with host-pathogen interaction, by studying transmigration of trypomastigotes into 3D spheroids. T. cruzi strains with similar infection dynamics in 2D monolayer cultures but with different in vivo behavior (CL Brener, virulent; SylvioX10 no virulent) presented different infection rates in spheroids (CL Brener ∼40%, SylvioX10 <10%). Confocal microscopy images evidenced that trypomastigotes from CL Brener and other highly virulent strains presented a great ability to transmigrate inside 3D spheroids: as soon as 4 hours post infection parasites were found at 50 µm in depth inside the spheroids. CL Brener trypomastigotes were evenly distributed and systematically observed in the space between cells, suggesting a paracellular route of transmigration to deepen into the spheroids. On the other hand, poor virulent strains presented a weak migratory capacity and remained in the external layers of spheroids (<10µm) with a patch-like distribution pattern. The invasiveness -understood as the ability to transmigrate deep into spheroids- was not a transferable feature between strains, neither by soluble or secreted factors nor by co-cultivation of trypomastigotes from invasive and non-invasive strains. We also studied the transmigration of recent T. cruzi isolates from children that were born congenitally infected, which showed a high migrant phenotype while an isolate form an infected mother (that never transmitted the infection to any of her 3 children) was significantly less migratory. Altogether, our results demonstrate that in a 3D microenvironment each strain presents a characteristic migration pattern and distribution of parasites in the spheroids that can be associated to their in vivo behavior. Certainly, the findings presented here could not have been studied with traditional 2D monolayer cultures.Author SummaryTrypanosoma cruzi is the protozoan parasite that causes Chaga’ disease, also known as American trypanosomiasis. Experimental models of the infection evidence that different strains of the parasite present different virulence in the host, which cannot be always reproduced in 2D monolayer cultures. Three dimensional (3D) cultures can be useful models to study complex host-parasite interactions because they mimic in vitro the microarchitecture of tissues and provide an environment similar to the encountered in natural infections. In particular, spheroids are small 3D aggregates of cells that interact with each other and with the extracellular matrix that they secrete resembling the original microenvironment both functionally and structurally. Spheroids have rarely been employed to explore infectious diseases and host-parasite interactions. In this work we studied how bloodstream trypomastigotes transmigrate through 3D spheroids mimicking the picture encountered by parasites in tissues soon after leaving circulation. We showed that the behavior of T. cruzi trypomastigotes in 3D cultures reflects their in vivo virulence: virulent strains transmigrate deeply into spheroids while non-virulent strains remain in the external layers of spheroids. Besides, this work demonstrates the usefulness of 3D cultures as an accurate in vitro model for the study of host-pathogen interactions that could not be addressed with conventional monolayer cultures.

scholarly journals Expanding the antimalarial toolkit: Targeting host–parasite interactions

2016 ◽  
Vol 213 (2) ◽  
pp. 143-153 ◽  
Author(s):  
Jean Langhorne ◽  
Patrick E. Duffy
Keyword(s):  
First Generation ◽  
Host Cells ◽  
Mammalian Host ◽  
Drug Resistant ◽  
Intracellular Growth ◽  
Partial Protection ◽  
Anopheles Mosquitoes ◽  
Host Parasite Interactions ◽  
New Research ◽  
Host Parasite

Recent successes in malaria control are threatened by drug-resistant Plasmodium parasites and insecticide-resistant Anopheles mosquitoes, and first generation vaccines offer only partial protection. New research approaches have highlighted host as well as parasite molecules or pathways that could be targeted for interventions. In this study, we discuss host–parasite interactions at the different stages of the Plasmodium life cycle within the mammalian host and the potential for therapeutics that prevent parasite migration, invasion, intracellular growth, or egress from host cells, as well as parasite-induced pathology.

In vivo response of Mesocestoides vogae to human insulin

Parasitology ◽  
2008 ◽  
Vol 136 (2) ◽  
pp. 203-209 ◽  
Author(s):  
L. CANCLINI ◽  
A. ESTEVES
Keyword(s):  
Human Insulin ◽  
Insulin Signalling ◽  
Reproduction Rate ◽  
Glucose Content ◽  
Parasitic Helminths ◽  
Host Parasite Interactions ◽  
Host Parasite ◽  
Different Levels ◽  
Mesocestoides Vogae

SUMMARYSuccessful host invasion by parasitic helminths involves detection and appropriate response to a range of host-derived signals. Insulin signal response pathways are ancient and highly-conserved throughout the metazoans. However, very little is known about helminth insulin signalling and the potential role it may play in host-parasite interactions. The response of Mesocestoides vogae (Cestoda: Cyclophyllidea) larvae to human insulin was investigated, focusing on tyrosine-phosphorylation status, glucose content, survival and asexual reproduction rate. Parasite larvae were challenged with different levels of insulin for variable periods. The parameters tested were influenced by human insulin, and suggested a host-parasite molecular dialogue.†

scholarly journals Trichomonas vaginalis: current understanding of host–parasite interactions

2011 ◽  
Vol 51 ◽  
pp. 161-175 ◽  
Author(s):  
Christopher M. Ryan ◽  
Natalia de Miguel ◽  
Patricia J. Johnson
Keyword(s):  
Drug Targets ◽  
Trichomonas Vaginalis ◽  
Molecular Data ◽  
Host Cells ◽  
Current Status ◽  
Rational Approach ◽  
Sexually Transmitted ◽  
Host Parasite Interactions ◽  
Future Challenges ◽  
Host Parasite

Trichomonas vaginalis is a sexually transmitted obligate extracellular parasite that colonizes the human urogenital tract. Despite being of critical importance to the parasite's survival relatively little is known about the mechanisms employed by T. vaginalis to establish an infection and thrive within its host. Several studies have focused on the interaction of the parasite with host cells and extracellular matrix, identifying multiple suspected T. vaginalis adhesins. However, with the exception of its surface lipophosphoglycan, the evidence supporting a role in adhesion is indirect or controversial for many candidate molecules. The availability of the T. vaginalis genome sequence paved the way for genomic analyses to search for proteins possibly involved in host–parasite interactions. Several proteomic analyses have also provided insight into surface, soluble and secreted proteins that may be involved in Trichomonas pathogenesis. Although the accumulation of molecular data allows for a more rational approach towards identifying drug targets and vaccine candidates for this medically important parasite, a continued effort is required to advance our understanding of its biology. In the present chapter, we review the current status of research aimed at understanding T. vaginalis pathogenesis. Applied experimental approaches, an overview of significant conclusions drawn from this research and future challenges are discussed.

A new technique for manipulating host–parasite interactions by low speed centrifugation

1978 ◽  
Vol 56 (5) ◽  
pp. 542-545 ◽  
Author(s):  
Margaret A. Waterman ◽  
James R. Aist ◽  
Herbert W. Israel
Keyword(s):  
Host Response ◽  
Host Cells ◽  
Plant Tissues ◽  
Powdery Mildew Fungus ◽  
Host Cytoplasm ◽  
Erysiphe Graminis Hordei ◽  
Host Parasite Interactions ◽  
Simultaneous Comparisons ◽  
A New Technique ◽  
Host Parasite

An apparatus and a method for centrifuging living, inoculated plant tissues were developed for studies of a cytoplasm-related host response of barley coleoptiles to penetration by the powdery mildew fungus Erysiphe graminis hordei. When the coleoptiles were attached to the apparatus with the long axes of the cells parallel to the centrifugal force, cytoplasm-rich and cytoplasm-poor zones were produced, permitting simultaneous comparisons of interactions in the presence or absence of host cytoplasm. The inner epidermis was inoculated and centrifuged for 12–14 h at 4750 × g. Desiccation was prevented by addition of liquids at the cut end of each coleoptile; the rest of the coleoptile was dry and suitable for inoculation with E. graminis conidia. Of the host cells, 50–80% had well-compacted cytoplasm, conidia developed penetration and infection structures, and the host response was restricted to cytoplasm-rich zones and was shown to be cytoplasm-dependent. Cytoplasmic streaming resumed within 10 min after centrifugation stopped, and 90–100% of the epidermal cells were actively streaming 3 h later. This centrifugation method could be adapted and applied to studies of the other host–parasite interactions.

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