Nuclear size and DNA content in host cells during first-generation schizogony of Eimeria zuernii

Parasitology ◽  
1977 ◽  
Vol 74 (2) ◽  
pp. 199-203 ◽  
Author(s):  
J. pasternak ◽  
M. A. Fernando ◽  
P. H. G. Stockdale ◽  
D. Weber
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Host Cell ◽  
Dna Content ◽  
Post Infection ◽  
First Generation ◽  
Host Cells ◽  
Proliferative Potential ◽  
Cell Nuclei ◽  
Major Target

The response of intestinal host-cell nuclei of calves infected with Eimeria zuernii 6 and 8 days post-infection was examined using Feulgen-DNA microspectrophotometry. The results show that nuclear hypertrophy is dissociated from DNA replication. In the light of previous work (Fernando, Pasternak, Barrell & Stockdale, 1974) it is surmised that the specificity of infection of cells by E. zuernii is not stringent, with the major target being non-proliferative cells. At most, 20% of the first-generation schizonts develop within cells that would have had proliferative potential and as a result some non-scheduled DNA synthesis occurs.

Changes of the DNA content of differentiating and adult macronuclei of the ciliate Loxodes magnus (Karyorelictida)

1980 ◽  
Vol 44 (1) ◽  
pp. 375-394
Author(s):  
N.N. Bobyleva ◽  
B.N. Kudrjavtsev ◽  
I.B. Raikov
Keyword(s):  
Cell Division ◽  
Dna Replication ◽  
Hydrochloric Acid ◽  
Dna Synthesis ◽  
Acid Hydrolysis ◽  
Gene Amplification ◽  
Dna Content

The DNA content of isolated micronuclei, differentiating macronuclei (macronuclear Anlagen), and adult macronuclei of Loxodes magnus was measured cytofluorimetrically in preparations stained with a Schiff-type reagent, auramine-SO2, following hydrochloric acid hydrolysis. The DNA content of the youngest macronuclear Anlagen proved to be the same as that of telophasic micronuclei (2 c). The Anlagen thus differentiate from micronuclei which are still in G1. The quantity of DNA in the macronuclear Anlagen thereafter rises to the 4-c level, simultaneously with DNA replication in the micronuclei which immediately follows mitosis. In non-dividing animals most micronuclei are already in G2. Adult macronuclei here contain on average 1.5 times more DNA than the micronuclei; their DNA content is about 5–6 c (in some individual nuclei, up to 10 c). These data are consistent with autoradiographic evidence indicating a weak DNA synthesis in the macronuclei of Loxodes and make likely the existence of partial DNA replication (e.g. gene amplification) in the macronuclei. The DNA content of adult macronuclei isolated from dividing animals proved to be significantly smaller than that of macronuclei isolated from non-dividing specimens of the same clone. In 3 clones studied, the former value amounted on average to 71–79, 78 and 95% of the latter, respectively. This drop of DNA content cannot be explained by ‘dilution’ of the old macronuclei with newly formed ones. The quantity of DNA in adult macronuclei thus seems to undergo cyclical changes correlated with cytokinesis, despite the fact that, in Loxodes magnus, the macronuclei themselves never divide and are simply segregated at every cell division. The macronuclei of Loxodes can be termed paradiploid or hyperdiploid.

scholarly journals Autoradiographic studies of DNA and histone synthesis in successive differentiation stages of pollen grain in Hyacinthus orientalis L.

2014 ◽  
Vol 50 (3) ◽  
pp. 367-380 ◽  
Author(s):  
Elżbieta Bednarska
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Vegetative Cell ◽  
Developmental Stages ◽  
Generative Cell ◽  
Pollen Grain ◽  
Cell Nuclei ◽  
Hyacinthus Orientalis ◽  
Histone Synthesis ◽  
Generative Cells

DNA and histone synthesis in five consecutive morphological stages of <em>Hyacinthus orientalis</em> L. pollen grain differentiation were studied autoradiographically. DNA synthesis was found to occur in both the generative and the vegetative cell. DNA replication in the generative cell took place when the generative cell was still adhered to the pollen grain wall but already devoid of callose wall. DNA synthesis in the generative cell slightly preceded that in the vegetative cell. Histones were synthesized in phase S of the generative and vegetative cell. In the generative cell histone synthesis also continued at a lower level after completion of DNA replication. In the developmental stages under study the nuclei of the generative cells were decidedly richer in lysine histones than vegetative cell nuclei.

scholarly journals Chlamydia-Infected Cells Continue To Undergo Mitosis and Resist Induction of Apoptosis

2004 ◽  
Vol 72 (1) ◽  
pp. 451-460 ◽  
Author(s):  
Whitney Greene ◽  
Yangming Xiao ◽  
Yanqing Huang ◽  
Grant McClarty ◽  
Guangming Zhong
Keyword(s):  
Dna Synthesis ◽  
Host Cell ◽  
Chlamydial Infection ◽  
Host Cells ◽  
Infected Host ◽  
Apoptosis Induction ◽  
Infected Cells ◽  
Induction Of Apoptosis

ABSTRACT Both anti- and proapoptotic activities have been reported to occur during chlamydial infection. To reconcile the apparent controversy, we compared host cell apoptotic responses to infection with 17 different chlamydial serovars and strains. None of the serovars caused any biologically significant apoptosis in the infected host cells. Host cells in chlamydia-infected cultures can continue to undergo DNA synthesis and mitosis. Chlamydia-infected cells are resistant to apoptosis induction, although the extent of the antiapoptotic ability varied between serovars. These observations have demonstrated that an anti- but not proapoptotic activity is the prevailing event in chlamydia-infected cultures.

scholarly journals Identification of an Arginine-Rich Motif in Human Papillomavirus Type 1 E1^E4 Protein Necessary for E4-Mediated Inhibition of Cellular DNA Synthesis In Vitro and in Cells

2008 ◽  
Vol 82 (18) ◽  
pp. 9056-9064 ◽  
Author(s):  
Sally Roberts ◽  
Sarah R. Kingsbury ◽  
Kai Stoeber ◽  
Gillian L. Knight ◽  
Phillip H. Gallimore ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Host Cell ◽  
S Phase ◽  
Human Papillomaviruses ◽  
Soluble Form ◽  
Cellular Dna ◽  
In Cells

ABSTRACT Productive infections by human papillomaviruses (HPVs) are restricted to nondividing, differentiated keratinocytes. HPV early proteins E6 and E7 deregulate cell cycle progression and activate the host cell DNA replication machinery in these cells, changes essential for virus synthesis. Productive virus replication is accompanied by abundant expression of the HPV E4 protein. Expression of HPV1 E4 in cells is known to activate cell cycle checkpoints, inhibiting G2-to-M transition of the cell cycle and also suppressing entry of cells into S phase. We report here that the HPV1 E4 protein, in the presence of a soluble form of the replication-licensing factor (RLF) Cdc6, inhibits initiation of cellular DNA replication in a mammalian cell-free DNA replication system. Chromatin-binding studies show that E4 blocks replication initiation in vitro by preventing loading of the RLFs Mcm2 and Mcm7 onto chromatin. HPV1 E4-mediated replication inhibition in vitro and suppression of entry of HPV1 E4-expressing cells into S phase are both abrogated upon alanine replacement of arginine 45 in the full-length E4 protein (E1^E4), implying that these two HPV1 E4 functions are linked. We hypothesize that HPV1 E4 inhibits competing host cell DNA synthesis in replication-activated suprabasal keratinocytes by suppressing licensing of cellular replication origins, thus modifying the phenotype of the infected cell in favor of viral genome amplification.

scholarly journals AN ANALYSIS OF DNA LOSS AND SYNTHESIS IN THE RAT ADRENAL MEDULLA NUCLEI UPON COLD STIMULATION

1966 ◽  
Vol 30 (2) ◽  
pp. 213-225 ◽  
Author(s):  
Maria Pia Viola-Magni
Keyword(s):  
Dna Synthesis ◽  
Adrenal Medulla ◽  
Cold Exposure ◽  
Dna Content ◽  
Room Temperature ◽  
Rapid Change ◽  
Cumulative Exposure ◽  
Cell Nuclei ◽  
Cold Stimulation ◽  
Dna Loss

The peculiar changes previously observed in DNA content of rat adrenal medulla cell nuclei upon intermittent cold exposure (15 hr at +4°C followed by 9 hr at room temperature) have been further studied with the aid of Feulgen histophotometry and H3-thymidine radioautography. The amount of DNA decreases progressively with increasing length of cold exposure until 300 hr (-32%). Later a rapid change takes place, whereby DNA content per nucleus returns to values which are slightly, but consistently lower than normal. At termination of a period of cumulative exposure to cold, an analysis of a whole-day experimental cycle shows that the DNA decrease is due to loss of DNA during cold exposure and that DNA synthesis occurs upon return to room temperature. The balance between these two processes can be divided into three stages: (a) loss of DNA up to 300 hr of cumulative cold exposure; (b) marked increase in DNA by 350 hr; (c) oscillation around zero or slightly negative at 400 hr and beyond. These variations are due to: (1) the extension of DNA synthesis into the period of cold exposure as clearly demonstrated by radioautography (stage b), and (2) a later still greater DNA loss (stage c) which partly offsets the increased synthesis. A complex pattern of adaptation of the adrenal medulla cells, as regards DNA content, to the repetitive cold stimulus is thus demonstrated.

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 Kaposi's Sarcoma-Associated Herpesvirus mRNA Accumulation in Nuclear Foci Is Influenced by Viral DNA Replication and Viral Noncoding Polyadenylated Nuclear RNA

2018 ◽  
Vol 92 (13) ◽  
Author(s):  
Tenaya K. Vallery ◽  
Johanna B. Withers ◽  
Joana A. Andoh ◽  
Joan A. Steitz
Keyword(s):  
Dna Replication ◽  
Viral Replication ◽  
Dna Synthesis ◽  
Host Cell ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Viral Dna ◽  
Viral Dna Replication ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACTKaposi's sarcoma-associated herpesvirus (KSHV), like other herpesviruses, replicates within the nuclei of its human cell host and hijacks host machinery for expression of its genes. The activities that culminate in viral DNA synthesis and assembly of viral proteins into capsids physically concentrate in nuclear areas termed viral replication compartments. We sought to better understand the spatiotemporal regulation of viral RNAs during the KSHV lytic phase by examining and quantifying the subcellular localization of select viral transcripts. We found that viral mRNAs, as expected, localized to the cytoplasm throughout the lytic phase. However, dependent on active viral DNA replication, viral transcripts also accumulated in the nucleus, often in foci in and around replication compartments, independent of the host shutoff effect. Our data point to involvement of the viral long noncoding polyadenylated nuclear (PAN) RNA in the localization of an early, intronless viral mRNA encoding ORF59-58 to nuclear foci that are associated with replication compartments.IMPORTANCELate in the lytic phase, mRNAs from Kaposi's sarcoma-associated herpesvirus accumulate in the host cell nucleus near viral replication compartments, centers of viral DNA synthesis and virion production. This work contributes spatiotemporal data on herpesviral mRNAs within the lytic host cell and suggests a mechanism for viral RNA accumulation. Our findings indicate that the mechanism is independent of the host shutoff effect and splicing but dependent on active viral DNA synthesis and in part on the viral noncoding RNA, PAN RNA. PAN RNA is essential for the viral life cycle, and its contribution to the nuclear accumulation of viral messages may facilitate propagation of the virus.

scholarly journals Infection of immune competent macrophages expressing functional Slc11a1 alters global gene expression, regulation of metal ions, and infection outcomes

2021 ◽  
Author(s):  
Lara N Janiszewski ◽  
Michael Minson ◽  
Mary A Allen ◽  
Robin D Dowell ◽  
Amy Palmer
Keyword(s):  
Gene Expression ◽  
Immune Response ◽  
Host Cell ◽  
Post Infection ◽  
Gene Expression Regulation ◽  
Divalent Cations ◽  
Host Cells ◽  
Published Data ◽  
Zinc Availability ◽  
Host Pathogen

Nutritional immunity involves cellular and physiological responses to invading pathogens, such as limiting iron availability, increasing exposure to bactericidal copper, and manipulating zinc      to restrict the growth of pathogens. Manipulation of zinc at the host-pathogen interface depends on both the pathogen’s identity and the nature of the host cell. Here we examine infection of bone marrow-derived macrophages from 129S6/SvEvTac mice by  Salmonella Typhimurium.  Unlike Balb/c and C57BL/6 mice, 129S6/SvEvTac mice possess a functional Slc11a1 (Nramp-1), a phagosomal transporter of divalent cations.  We carried out global RNA sequencing upon treatment with live or heat-killed  Salmonella  at 2 Hrs and 18 Hrs post-infection and observed widespread changes in metal transport, metal-dependent, and metal homeostasis genes, suggesting significant remodeling of iron, copper, and zinc availability by host cells. Changes in host cell gene expression suggest infection increases cytosolic zinc while simultaneously limiting zinc within the phagosome. Using a genetically encoded sensor, we demonstrate that cytosolic labile zinc increases 36-fold 12 hrs post-infection.  Further, manipulation of zinc in the media alters bacterial clearance and replication, with zinc depletion inhibiting both processes. Comparing our results to published data on infection of C57BL/6 macrophages revealed notable differences in metal regulation and the global immune response, with 129S6 macrophages transitioning from M1 to M2 polarization over the course of infection and showing signs of recovery. Our results reveal that functional Slc11a1 profoundly affects the transcriptional landscape upon infection. Further, our results indicate that manipulation of zinc at the host-pathogen interface is more nuanced than that of iron or copper. 129S6 macrophage leverage intricate means of manipulating zinc availability and distribution to limit the pathogen’s access to zinc while simultaneously ensuring sufficient zinc to support the immune response.

scholarly journals Mitochondrial growth and DNA synthesis occur in the absence of nuclear DNA replication in fission yeast

1990 ◽  
Vol 97 (3) ◽  
pp. 509-516 ◽  
Author(s):  
S. Sazer ◽  
S.W. Sherwood
Keyword(s):  
Mitochondrial Dna ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Fission Yeast ◽  
Dna Content ◽  
Nuclear Dna ◽  
Equal Distribution ◽  
Daughter Cells ◽  
Mitochondrial Dna Content ◽  
Mitochondrial Volume

Cell growth and division require the doubling of cellular constituents followed by their equal distribution to the two daughter cells. Within a growing population, the ratio of mitochondrial to cellular volume is maintained, as is the number of mitochondrial genomes per cell. The mechanisms responsible for coordinating nuclear and mitochondrial DNA synthesis, and for balancing increases in cell and mitochondrial size are not well understood. In studies of the fission yeast Schizosaccharomyces pombe we quantified cellular and mitochondrial DNA content by both Southern blot analysis and flow cytometry of cells stained with a variety of DNA-binding fluorochromes, which we show are able to detect nuclear and mitochondrial DNA with different efficiencies. In the conditional cell division cycle mutant cdc10, which is unable to initiate nuclear DNA synthesis, we found that there was an increase in the mitochondrial DNA content in the absence of nuclear DNA replication. This demonstrates that mitochondrial and nuclear DNA synthesis are not obligately linked. We also show that mitochondrial DNA replication is not required for the increase in mitochondrial size that occurs as cells elongate, although this results in a decrease in the ratio of mitochondrial DNA to mitochondrial volume.

scholarly journals Antiviral Effects of Artesunate on Polyomavirus BK Replication in Primary Human Kidney Cells

2013 ◽  
Vol 58 (1) ◽  
pp. 279-289 ◽  
Author(s):  
Biswa Nath Sharma ◽  
Manfred Marschall ◽  
Stian Henriksen ◽  
Christine Hanssen Rinaldo
Keyword(s):  
Dna Replication ◽  
Protein Expression ◽  
Host Cell ◽  
T Antigen ◽  
Host Cells ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Antiviral Effects ◽  
Mrna And Protein Expression ◽  
Polyomavirus Bk

ABSTRACTPolyomavirus BK (BKV) causes polyomavirus-associated nephropathy (PyVAN) and hemorrhagic cystitis (PyVHC) in renal and bone marrow transplant patients, respectively. Antiviral drugs with targeted activity against BKV are lacking. Since the antimalarial drug artesunate was recently demonstrated to have antiviral activity, the possible effects of artesunate on BKV replication in human primary renal proximal tubular epithelial cells (RPTECs), the host cells in PyVAN, were explored. At 2 h postinfection (hpi), RPTECs were treated with artesunate at concentrations ranging from 0.3 to 80 μM. After one viral replication cycle (approximately 72 hpi), the loads of extracellular BKV DNA, reflecting viral progeny production, were reduced in a concentration-dependent manner. Artesunate at 10 μM reduced the extracellular BKV load by 65%; early large T antigen mRNA and protein expression by 30% and 75%, respectively; DNA replication by 73%; and late VP1 mRNA and protein expression by 47% and 64%, respectively. Importantly, the proliferation of RPTECs was also inhibited in a concentration-dependent manner. At 72 hpi, artesunate at 10 μM reduced cellular DNA replication by 68% and total metabolic activity by 47%. Cell impedance and lactate dehydrogenase measurements indicated a cytostatic but not a cytotoxic mechanism. Flow cytometry and 5-ethynyl-2′-deoxyuridine incorporation revealed a decreased number of cells in S phase and suggested cell cycle arrest in G0or G2phase. Both the antiproliferative and antiviral effects of artesunate at 10 μM were reversible. Thus, artesunate inhibits BKV replication in RPTECs in a concentration-dependent manner by inhibiting BKV gene expression and genome replication. The antiviral mechanism appears to be closely connected to cytostatic effects on the host cell, underscoring the dependence of BKV on host cell proliferative functions.

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