Cytochemical localization of acid phosphatase in endophyte cells of the semiparasitic angiosperm Comandra umbellata (Santalaceae)

1977 ◽  
Vol 55 (4) ◽  
pp. 470-475 ◽  
Author(s):  
Ronald Toth ◽  
Job Kuijt
Keyword(s):  
Acid Phosphatase ◽  
Host Cell ◽  
Lysosomal Enzymes ◽  
Large Scale ◽  
Turgor Pressure ◽  
Host Cells ◽  
Cytochemical Localization ◽  
Host Cell Membranes ◽  
Host Parasite ◽  
Tip Cells

Acid phosphatase (orthophosphoric-monoester phosphohydrolase (acid optimum), EC 3.1.3.2) has been localized in cells at the growing tips of the endophyte in the semiparasitic angiosperm Comandra umbellata. Lysosomes in tip cells release their contents into the apoplast at the host–parasite interface before any possible release of enzyme from disrupted host lysosomes. However, a large-scale digestion of host cells does not occur. Parasite cells release acid phosphatase and probably other lysosomal enzymes which appear to disrupt host cell membranes causing a loss in turgor pressure followed by the eventual crushing of host cells by the invading endophyte.

scholarly journals Drug Discovery for Chagas Disease: Impact of Different Host Cell Lines on Assay Performance and Hit Compound Selection

2019 ◽  
Vol 4 (2) ◽  
pp. 82 ◽  
Author(s):  
Caio Haddad Franco ◽  
Laura Maria Alcântara ◽  
Eric Chatelain ◽  
Lucio Freitas-Junior ◽  
Carolina Borsoi Moraes
Keyword(s):  
Drug Discovery ◽  
Host Cell ◽  
Cell Lines ◽  
Chagas Disease ◽  
Host Cells ◽  
Mammalian Cell Lines ◽  
Starting Point ◽  
Disease Impact ◽  
Screening Assays ◽  
Host Parasite

Cell-based screening has become the major compound interrogation strategy in Chagas disease drug discovery. Several different cell lines have been deployed as host cells in screening assays. However, host cell characteristics and host-parasite interactions may play an important role when assessing anti-T. cruzi compound activity, ultimately impacting on hit discovery. To verify this hypothesis, four distinct mammalian cell lines (U2OS, THP-1, Vero and L6) were used as T. cruzi host cells in High Content Screening assays. Rates of infection varied greatly between different host cells. Susceptibility to benznidazole also varied, depending on the host cell and parasite strain. A library of 1,280 compounds was screened against the four different cell lines infected with T. cruzi, resulting in the selection of a total of 82 distinct compounds as hits. From these, only two hits were common to all four cell lines assays (2.4%) and 51 were exclusively selected from a single assay (62.2%). Infected U2OS cells were the most sensitive assay, as 55 compounds in total were identified as hits; infected THP-1 yielded the lowest hit rates, with only 16 hit compounds. Of the selected hits, compound FPL64176 presented selective anti-T. cruzi activity and could serve as a starting point for the discovery of new anti-chagasic drugs.

scholarly journals Genetic variability in the expression of the SARS-CoV-2 host cell entry factors across populations

2020 ◽  
Author(s):  
Lourdes Ortiz-Fernández ◽  
Amr H Sawalha
Keyword(s):  
Host Cell ◽  
Viral Entry ◽  
Quantitative Measure ◽  
Individual Variability ◽  
Host Cells ◽  
Genetic Determinants ◽  
Angiotensin Converting Enzyme 2 ◽  
African Populations ◽  
Host Cell Entry ◽  
Host Cell Membranes

AbstractThe entry of SARS-CoV-2 into host cells is dependent upon angiotensin-converting enzyme 2 (ACE2), which serves as a functional attachment receptor for the viral spike glycoprotein, and the serine protease TMPRSS2 which allows fusion of the viral and host cell membranes. We devised a quantitative measure to estimate genetic determinants of ACE2 and TMPRSS2 expression and applied this measure to >2,500 individuals. Our data show significant variability in genetic determinants of ACE2 and TMPRSS2 expression among individuals and between populations, and demonstrate a genetic predisposition for lower expression levels of both key viral entry genes in African populations. These data suggest that genetic factors might lead to lower susceptibility for SARS-CoV-2 infection in African populations and that host genetics might help explain inter-individual variability in disease susceptibility and severity of COVID-19.

INCORPORATION OF CYTIDINE-H3 INTO THE PRIMARY LEAF OF WHEAT FOLLOWING INFECTION WITH PUCCINIA RECONDITA ROB. EX DESM.

1963 ◽  
Vol 41 (10) ◽  
pp. 1501-1508 ◽  
Author(s):  
J. Nielsen ◽  
R. Rohringer
Keyword(s):  
Host Cell ◽  
Ribonucleic Acid ◽  
Host Tissue ◽  
Host Cells ◽  
Puccinia Recondita ◽  
Infected Leaf ◽  
Cell Nuclei ◽  
Short Term ◽  
Wheat Leaves ◽  
Host Parasite

In short-term experiments, cytidine-H3 was fed to rusted and healthy areas of wheat leaves. The incorporated activity, presumably residing in ribonucleic acid, was detected by microautoradiographic methods. Most of the label was found to be incorporated in host cell nuclei. Little incorporation occurred in extranuclear structures of host cells, including chloroplasts. Very long autoradiographic exposure times failed to reveal any incorporation into the fungus.Host cells in infected leaf areas contained considerably less label in their nuclei and cytoplasm than those in cells further from the site of infection. This effect of the fungus extended over some distance into uninvaded host tissue, but not beyond 100 μ from the periphery of the mycelium. The decreased cytidine incorporation in the affected host tissue is not caused by possible changes in pool size of endogenous cytidine. The significance of these results for the host–parasite interaction is briefly discussed.

scholarly journals Mechanical Fractionation Reveals Structural Requirements for Enteropathogenic Escherichia coli Tir Insertion into Host Membranes

2000 ◽  
Vol 68 (7) ◽  
pp. 4344-4348 ◽  
Author(s):  
Annick Gauthier ◽  
Myriam de Grado ◽  
B. Brett Finlay
Keyword(s):  
Escherichia Coli ◽  
Host Cell ◽  
Hela Cells ◽  
Protein Delivery ◽  
Mammalian Cells ◽  
Host Cells ◽  
Host Cell Membrane ◽  
Bacterial Proteins ◽  
Host Cell Membranes ◽  
Triton X

ABSTRACT Enteropathogenic Escherichia coli (EPEC) inserts its receptor for intimate adherence (Tir) into host cell membranes by using a type III secretion system. Detergents are frequently used to fractionate infected host cells to investigate bacterial protein delivery into mammalian cells. In this study, we found that the Triton X-100-soluble membrane fraction from EPEC-infected HeLa cells was contaminated with bacterial proteins. We therefore applied a mechanical method of cell lysis and ultracentrifugation to fractionate infected HeLa cells to investigate the biology and biochemistry of Tir delivery and translocation. This method demonstrates that the translocation of Tir into the host cell membrane requires its transmembrane domains, but not tyrosine phosphorylation or binding to Tir's ligand, intimin.

Host – parasite relationships between the fungus Leptosphaerulina crassiasca and peanut

1992 ◽  
Vol 70 (9) ◽  
pp. 1724-1733 ◽  
Author(s):  
Mei-Lee Wu ◽  
Richard T. Hanlin
Keyword(s):  
Cell Wall ◽  
Host Cell ◽  
Germ Tube ◽  
Light And Electron Microscopy ◽  
Host Cells ◽  
Detached Leaves ◽  
Host Cell Wall ◽  
Host Parasite ◽  
Germ Tubes ◽  
Infection Hypha

The mode of penetration and infection of the peanut leaf by Leptosphaerulina crassiasca were studied by means of light and electron microscopy. The attachment of the multicellular ascospores to the leaf surface was by a mucilagenous sheath that covered the ascospores at maturity. This sheath expanded rapidly in moisture and it extended along the germ tube as it elongated. Two types of germ tubes appeared to be formed, a short one and a relatively long one. Short germ tubes were not delimited by septa, and they penetrated the cuticle and host epidermal cell wall directly without appressorium formation. Penetration occurred 2–6 h after inoculation. The wall was breached by a relatively broad infection hypha that expanded in width inside the host cell wall. The lack of mechanical rupture at the infection site indicated that penetration may involve enzymatic activity. Intracellular hyphae were present in the epidermal cells, but only intercellular hyphae occurred in the palisade and spongy mesophyll tissues. The intercellular hyphae were frequently appressed to the outer surface of the host cell wall. Infected areas rarely exceeded 1 mm in diameter, and they were only sparsely colonized by hyphae of the pathogen. Host cells in the vicinity of hyphae underwent senescence and death. One to 2 months after inoculation, pseudothecia formed in the dead tissues of detached leaves. In some instances the presence of penetration hyphae by short germ tubes induced the formation of a papilla inside the host cell wall, which either restricted growth of the infection hypha or resulted in the death of the germ tube and the cell from which it arose. Long germ tubes were delimited by simple septa and they terminated in an appressorium; however, details of their behavior were not studied. Key words: Arachis hypogaea, Ascomycotina, Dothideales, leaf scorch, pepper spot.

scholarly journals Retrovirus Entry by Endocytosis and Cathepsin Proteases

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Yoshinao Kubo ◽  
Hideki Hayashi ◽  
Toshifumi Matsuyama ◽  
Hironori Sato ◽  
Naoki Yamamoto
Keyword(s):  
Host Cell ◽  
Leukemia Virus ◽  
Retroviral Vectors ◽  
Viral Envelope ◽  
Host Cells ◽  
Target Cells ◽  
Cellular Mechanisms ◽  
Cathepsin Proteases ◽  
Transfer Genes ◽  
Host Cell Membranes

Retroviruses include infectious agents inducing severe diseases in humans and animals. In addition, retroviruses are widely used as tools to transfer genes of interest to target cells. Understanding the entry mechanism of retroviruses contributes to developments of novel therapeutic approaches against retrovirus-induced diseases and efficient exploitation of retroviral vectors. Entry of enveloped viruses into host cell cytoplasm is achieved by fusion between the viral envelope and host cell membranes at either the cell surface or intracellular vesicles. Many animal retroviruses enter host cells through endosomes and require endosome acidification. Ecotropic murine leukemia virus entry requires cathepsin proteases activated by the endosome acidification. CD4-dependent human immunodeficiency virus (HIV) infection is thought to occur via endosomes, but endosome acidification is not necessary for the entry whereas entry of CD4-independent HIVs, which are thought to be prototypes of CD4-dependent viruses, is low pH dependent. There are several controversial results on the retroviral entry pathways. Because endocytosis and endosome acidification are complicatedly controlled by cellular mechanisms, the retrovirus entry pathways may be different in different cell lines.

The Alternaria brassicae – Nectria inventa host–parasite interface

1977 ◽  
Vol 55 (4) ◽  
pp. 448-454 ◽  
Author(s):  
A. Tsuneda ◽  
W. P. Skoropad
Keyword(s):  
Cell Wall ◽  
Host Cell ◽  
Host Cells ◽  
Alternaria Brassicae ◽  
Adhesive Material ◽  
Large Hole ◽  
Mature Conidium ◽  
Host Cell Wall ◽  
Host Parasite

The Verticillium state of Nectria inventa is a destructive parasite of Alternaria brassicae. Tropic growth of parasite hyphae towards hyphae and conidia of A. brassicae occurs in the vicinity of the host. Upon contact, the parasite hyphae often form appressorium-like bodies on the host cells and produce fibrous adhesive material at the host–parasite interface. Conidia are penetrated more commonly than hyphae. Penetration of the septa in hyphae results in a separation of cells. Penetration of a mature conidium also occurs commonly at a septum. The presence of a large hole in the wall of the host cell and the meshwork of material at the penetration site suggest that enzymatic breakdown of host cell wall occurs. Juvenile conidia are penetrated usually at the basal pore.

scholarly journals Endocytosis of the symbiotic dinoflagellate Symbiodinium microadriaticum Freudenthal by endodermal cells of the scyphistomae of Cassiopeia xamachana and resistance of the algae to host digestion

1983 ◽  
Vol 64 (1) ◽  
pp. 195-212
Author(s):  
W.K. Fitt ◽  
R.K. Trench
Keyword(s):  
Acid Phosphatase ◽  
Host Cell ◽  
Phosphatase Activity ◽  
Acid Phosphatase Activity ◽  
Host Cells ◽  
Symbiodinium Microadriaticum ◽  
Food Vacuoles ◽  
Secondary Lysosomes ◽  
Endodermal Cells ◽  
Cassiopeia Xamachana

The ingestion and fate of four types of particles by endodermal cells of the scyphistomae of Cassiopeia xamachana were investigated by scanning and transmission electron microscopy. Ferritin was endocytosed pinocytotically by invagination of the plasmalemma. These small pinocytotic vesicles fuse with other similar vesicles to form larger ferritin-containing vacuoles, which eventually fuse with lysosomes. Such secondary lysosomes exhibit acid phosphatase activity. The co-occurrence of acid phosphatase activity and ferritin in secondary lysosomes achieved maximum frequency within 2 h of uptake of ferritin and was evident for at least 4 h following uptake. Artemia particles, live freshly isolated symbiotic algae (Symbiodinium microadriaticum), and heat-killed S. microadriaticum are phagocytosed by endodermal cells. Ferritin-labelled lysosomes fused with food vacuoles containing particles of Artemia. Vacuoles containing heat-killed S. microadriaticum also showed evidence of phago-lysosome fusion. S. microadriaticum in situ (i.e. in host cells) after 3 days exposure to the photosynthetic inhibitor, 3-(3-4-dichlorophenyl)-1,1-dimethylurea, appeared degenerate, and were found in loose-fitting host vacuoles, many in mid and apical portions of the host cell. More than 70% of these vacuoles with moribund algae contained the ferritin label, indicating that lysosome fusion had occurred. In contrast, live S. microadriaticum in control animals were almost always found at the base of the host cell in individual tight-fitting vacuoles with no evidence of lysosome fusion. Live S. microadriaticum apparently escape host digestion by prohibiting the fusion of lysosomes with the vacuole in which they reside. Vacuoles containing defunct algal symbionts, in contrast, were subject to lysosomal attack.

scholarly journals A Scalable Screening of E. coli Strains for Recombinant Protein Expression

2021 ◽  
Author(s):  
Luana G. Morão ◽  
Lívia R. Manzine ◽  
Angélica Luana C. Barra ◽  
Lívia Oliveira D. Clementino ◽  
Raíssa F. Gutierrez ◽  
...  
Keyword(s):  
Protein Expression ◽  
Gene Cloning ◽  
Host Cell ◽  
Structural Biology ◽  
Soluble Protein ◽  
Large Scale ◽  
Host Cells ◽  
The Arctic ◽  
Fusion Tag ◽  
Selection Of

AbstractStructural biology projects are highly dependent on the large-scale expression of soluble protein and, for this purpose, heterologous expression using bacteria or yeast as host systems are usually employed. In this scenario, some of the parameters to be optimized include (i) those related to the protein construct, such as the use of a fusion protein, the choice for an N-terminus fusion/tag or a C-terminus fusion/tag; (ii) those related to the expression stage, such as the concentration and selection of inducer agent and temperature expression and (iii) the choice of the host system, which includes the selection of a prokaryotic or eukaryotic cell and the adoption of a strain. The optimization of some of the parameters related to protein expression, stage (ii), is straightforward. On the other hand, the determination of the most suitable parameters related to protein construction requires a new cycle of gene cloning, while the optimization of the host cell is less straightforward. Here, we evaluated a scalable approach for the screening of host cells for protein expression in a structural biology pipeline. We evaluated six Escherichia coli strains looking for the best yield in soluble protein expression using the same strategy for protein construction and gene cloning. For the genes used in this experiment, the Arctic Express (DE3) strain resulted in better yields of soluble proteins. We propose that screening of host cell/strain is feasible, even for smaller laboratories and the experiment as proposed can easily be scalable to a high-throughput approach.

scholarly journals Targeting Lipid Rafts as a Strategy Against Coronavirus

2021 ◽  
Vol 8 ◽  
Author(s):  
Maurizio Sorice ◽  
Roberta Misasi ◽  
Gloria Riitano ◽  
Valeria Manganelli ◽  
Stefano Martellucci ◽  
...  
Keyword(s):  
Host Cell ◽  
Lipid Rafts ◽  
Viral Envelope ◽  
Host Cells ◽  
Spike Protein ◽  
Membrane Microdomains ◽  
Virus Infectivity ◽  
Necrosis Factor Alpha ◽  
Functional Membrane ◽  
Host Cell Membranes

Lipid rafts are functional membrane microdomains containing sphingolipids, including gangliosides, and cholesterol. These regions are characterized by highly ordered and tightly packed lipid molecules. Several studies revealed that lipid rafts are involved in life cycle of different viruses, including coronaviruses. Among these recently emerged the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The main receptor for SARS-CoV-2 is represented by the angiotensin-converting enzyme-2 (ACE-2), although it also binds to sialic acids linked to host cell surface gangliosides. A new type of ganglioside-binding domain within the N-terminal portion of the SARS-CoV-2 spike protein was identified. Lipid rafts provide a suitable platform able to concentrate ACE-2 receptor on host cell membranes where they may interact with the spike protein on viral envelope. This review is focused on selective targeting lipid rafts components as a strategy against coronavirus. Indeed, cholesterol-binding agents, including statins or methyl-β-cyclodextrin (MβCD), can affect cholesterol, causing disruption of lipid rafts, consequently impairing coronavirus adhesion and binding. Moreover, these compounds can block downstream key molecules in virus infectivity, reducing the levels of proinflammatory molecules [tumor necrosis factor alpha (TNF-α), interleukin (IL)-6], and/or affecting the autophagic process involved in both viral replication and clearance. Furthermore, cyclodextrins can assemble into complexes with various drugs to form host–guest inclusions and may be used as pharmaceutical excipients of antiviral compounds, such as lopinavir and remdesivir, by improving bioavailability and solubility. In conclusion, the role of lipid rafts-affecting drugs in the process of coronavirus entry into the host cells prompts to introduce a new potential task in the pharmacological approach against coronavirus.

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