scholarly journals Effect of N-hydroxyurea, mitomycin C and actinomycin D on tumour formation on the leaves of Kalanchoe daigremontiana

2014 ◽  
Vol 52 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Józef Koawalczyk
Keyword(s):  
Dna Synthesis ◽  
Actinomycin D ◽  
Plant Cells ◽  
Host Tissue ◽  
Host Cells ◽  
Tumour Formation ◽  
Second Period ◽  
Dna Synthesis Inhibitors ◽  
Kalanchoë Daigremontiana ◽  
Kalanchoe Daigremontiana

The leaves of <em>Kalanchoe daigremontiana</em> wounded and infected with <em>Agrobacterium tumefaciens</em> were treated with single doses of inhibitors (hydroxyurea - 190, mitomycin - 0.5, actinomycin - 2 µ,g per leaf). After delaying the time' of dosage of inhibitors during five days after inoculation, changes in susceptibility of the system to antitumorous activity of analysed compounds were observed. In several hours after inoculation (period of the bacteria metabolic activity in wounds) all the inhibitors prevent strongly the tumour formation. At the time between 14 and 72 hours after inoculation, including the phase of tumour induction, the system becomes sensitive to the DNA synthesis inhibitors, particularly hydroxyurea. The intensified action of actinomycin appears again only about 60 hours after inoculation and lasts till the end of experiment (the initiation of the transformed plant cell proliferation). According to the literature the antitumorous effect of inhibitors could be connected with their action on the bacteria metabolism inside the host tissue. The activities of hydroxyurea and mitomycin in the second period correspond with the intensive DNA synthesis in plant cells, which is induced by wounding. The effect of actinomycin D in 60 hours after inoculation could depend upon the inhibition of the proliferation of the transformed host cells.

scholarly journals Evidence that the Synchronized Production of New Basal Bodies is not Associated with Dna Synthesis in Stentor Coeruleus

1972 ◽  
Vol 11 (2) ◽  
pp. 621-637
Author(s):  
K. B. YOUNGER ◽  
S. BANERJEE ◽  
J. K. KELLEHER ◽  
M. WINSTON ◽  
LYNN MARGULIS
Keyword(s):  
Dna Synthesis ◽  
Ethidium Bromide ◽  
Basal Body ◽  
Actinomycin D ◽  
Thymidine Incorporation ◽  
Basal Bodies ◽  
Rna And Protein Synthesis ◽  
Stentor Coeruleus ◽  
Body Production ◽  
Dna Synthesis Inhibitors

Stentors were induced to produce synchronously thousands of new ciliated oral membranellar band basal bodies in less than 3 h. DNA synthesis does not accompany this process, as determined by [3H]thymidine incorporation into isolated bands and by sensitivity to DNA synthesis inhibitors (mitomycin C, ethidium bromide, cytosine arabinoside and hydroxyurea). Yet DNA could be detected in the cortex and the band at basal body sites by autoradiography. Since [3H]thymidine incorporation into membranellar band was eliminated in concentrations of ethidium bromide that had no effect on basal body formation, the previous reports of ciliate kinetosomal (basal body) DNA are interpreted as due to mitochondrial contamination. Specific cortical patterns of DNA that could have been easily misinterpreted as basal body-related were especially apparent in autoradiographs using [3H]actinomycin D as a ‘stain’. In no experiment involving induced basal body regeneration could evidence be found for a correlation between new basal body production and DNA synthesis; RNA and protein synthesis correlated with basal body and cilia regeneration were, however, easily detected by the same techniques. We concluded that there is no evidence that basal body DNA synthesis is required for new basal body production.

scholarly journals N-hydroxyurea, mitomycin C and actinomycin D activity in the process of tumour formation on the primary leaves of the 'Pinto' bean

2014 ◽  
Vol 49 (1-2) ◽  
pp. 63-76
Author(s):  
Aldona Rennert
Keyword(s):  
Mitomycin C ◽  
Actinomycin D ◽  
Plant Cells ◽  
Maximal Effect ◽  
Critical Periods ◽  
Tumour Formation ◽  
Pinto Bean ◽  
Host Pathogen ◽  
Pinto Beans ◽  
Bean Leaves

Mitomycin C (MC), N-hydroxyurea (HU) and actinomycin D (AD) inhibit tumour formation on the primary leaves of Pinto beans. <em>Agrobacterium</em> tumefaciens was inoculated into bean leaves with application of the above named inhibitors at various times. It was found that MC action is strongest during inoculation and immediately after it, the maximal effect of HU take place within 12 h after inoculation, whereas the antitumour action of AD starts as late as 12 h after leaf inoculation. In view of the different degree of susceptibility of bacteria and plant cells to the inhibitors applied, the above described results allowed to distinguish three critical periods in the process of tumour formation in the tested host-pathogen system.

scholarly journals Phases of crown-gall transformation susceptible to hydroxyurea

2014 ◽  
Vol 53 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Aldona Rennert ◽  
Józef Kowalczyk ◽  
Halina Pajkowska
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Crown Gall ◽  
Pathogenic Bacteria ◽  
Direct Action ◽  
Plant Cells ◽  
Induction Phase ◽  
Bacterial Strains ◽  
Tumour Formation ◽  
Kalanchoë Daigremontiana ◽  
Anti Tumour Effect

With the use of bacterial strains, both sensitive and resistant to hydroxyurea the action of this inhibitor on tumour formation on the leaves of <em>Kalanchoe daigremontiana</em> infected with <em>Agrobacterium tumefaciens</em> was tested for five days after inoculation. The results are in agreement with the opinion that the anti-tumour effect of hydroxyurea applied in the induction phase (between 18 and 60 h after inoculation) is the result of its direct action on plant cells, whereas inhibition of tumour formation by the inhibitor in the inoculation period depends on its action on the pathogenic bacteria.

scholarly journals Perturbation of host autophagy by the Irish potato famine pathogen

2014 ◽  
Vol 70 (a1) ◽  
pp. C826-C826
Author(s):  
Abbas Maqbool ◽  
Richard Richard ◽  
Tolga Bozkurt ◽  
Yasin Dagdas ◽  
Khaoula Belhai ◽  
...  
Keyword(s):  
Host Cell ◽  
Plant Cells ◽  
Irish Potato ◽  
Effector Proteins ◽  
Host Cells ◽  
Cell Physiology ◽  
Biochemical Basis ◽  
The Impact ◽  
Potato Famine ◽  
Irish Potato Famine

Autophagy is a catabolic process involving degradation of dysfunctional cytoplasmic components to ensure cellular survival under starvation conditions. The process involves formation of double-membrane vesicles called autophagosomes and delivery of the inner constituents to lytic compartments. It can also target invading pathogens, such as intracellular bacteria, for destruction and is thus implicated in innate immune pathways [1]. In response, certain mammalian pathogens deliver effector proteins into host cells that inhibit autophagy and contribute to enabling parasitic infection [2]. Pyhtophthora infestans, the Irish potato famine pathogen, is a causative agent of late blight disease in potato and tomato crops. It delivers a plethora of modular effector proteins into plant cells to promote infection. Once inside the cell, RXLR-type effector proteins engage with host cell proteins, to manipulate host cell physiology for the benefit of the pathogen. As plants lack an adaptive immune system, this provides a robust mechanism for pathogens to circumvent host defense. PexRD54 is an intracellular RXLR-type effector protein produced by P. infestans. PexRD54 interacts with potato homologues of autophagy protein ATG8 in plant cells. We have been investigating the structural and biochemical basis of the PexRD54/ATG8 interaction in vitro. We have purified PexRD54 and ATG8 independently and in complex from E. coli. Using protein/protein interaction studies we have shown that PexRD54 binds ATG8 with sub-micromolar affinity. We have also determined the structure of PexRD54 in the presence of ATG8. This crystal structure provides key insights into how the previously reported WY-fold of oomycete RXLR-type effectors [3] can be organized in multiple repeats. The structural data also provides insights into the interaction between PexRD54 and ATG8, suggesting further experiments to understand the impact of this interaction on host cell physiology and how this benefits the pathogen.

Effectors of biotrophic fungal plant pathogens

2010 ◽  
Vol 37 (10) ◽  
pp. 913 ◽  
Author(s):  
Pamela H. P. Gan ◽  
Maryam Rafiqi ◽  
Adrienne R. Hardham ◽  
Peter N. Dodds
Keyword(s):  
Plant Tissue ◽  
Fungal Pathogen ◽  
Plant Pathogens ◽  
Plant Cells ◽  
Host Cells ◽  
Plant Proteins ◽  
Living Plant ◽  
Host Cytoplasm ◽  
Fungal Plant Pathogens ◽  
Biotrophic Fungi

Plant pathogenic biotrophic fungi are able to grow within living plant tissue due to the action of secreted pathogen proteins known as effectors that alter the response of plant cells to pathogens. The discovery and identification of these proteins has greatly expanded with the sequencing and annotation of fungal pathogen genomes. Studies to characterise effector function have revealed that a subset of these secreted pathogen proteins interact with plant proteins within the host cytoplasm. This review focuses on the effectors of intracellular biotrophic and hemibiotrophic fungal plant pathogens and summarises advances in understanding the roles of these proteins in disease and in elucidating the mechanism of fungal effector uptake into host cells.

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