scholarly journals OBSERVATIONS ON THE UPTAKE OF TRITIATED THYMIDINE IN THE PRONUCLEI OF FERTILIZED SAND DOLLAR EMBRYOS

1961 ◽  
Vol 10 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Eva B. Simmel ◽  
David A. Karnofsky
Keyword(s):  
Dna Synthesis ◽  
Nuclear Localization ◽  
Tritiated Thymidine ◽  
Nuclear Material ◽  
Thymidine Uptake ◽  
Sand Dollar ◽  
Male And Female ◽  
Daughter Cells ◽  
Minute Period ◽  
Independent Replication

Following fertilization of the egg of the sand dollar Echinarachnius parma, tritiated thymidine (H3TDR) was taken up independently by the male and female pronuclei beginning within about 15 to 20 minutes, and the labeled pronuclei fused at about 30 to 40 minutes. At cleavage 90 minutes later the labeled nuclear material was distributed to both daughter cells. Unfertilized eggs and sperm exposed to H3TDR did not show nuclear localization of thymidine. DNA replication, thus, is initiated in the haploid pronuclei shortly after fertilization and prior to fusion. The major portion of DNA synthesis, as evidenced by thymidine uptake, appears to be during a 20 to 30 minute period after fertilization. Fertilization is associated with the activation of a mechanism which initiates early and independent replication of DNA in both the male and female pronuclei.

Mediators of the mitogenic action of human V1vascular vasopressin receptors

2000 ◽  
Vol 279 (5) ◽  
pp. H2529-H2539 ◽  
Author(s):  
Marc Thibonnier ◽  
Doreen M. Conarty ◽  
Christine L. Plesnicher
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Protein Kinase ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
Tritiated Thymidine ◽  
Chinese Hamster ◽  
Mitogen Activated Protein Kinase ◽  
Thymidine Uptake ◽  
Mitogenic Action

Arginine vasopressin (AVP) activation of V1 vascular receptors (V1Rs) stimulates cell growth and proliferation in different tissues via cellular signaling pathways that remain to be identified. To explore the intracellular mediators of the mitogenic action of V1R, Chinese hamster ovary (CHO) cells were stably transfected with the human V1R cDNA clone we isolated previously. We assessed AVP effects on kinase activation (immunoblotting with phosphospecific antibodies), DNA synthesis (tritiated thymidine uptake), cell cycle progression (flow cytometry analysis after nuclear labeling with propidium iodide), and cell proliferation (conversion of the colorimetric reagent MTS) in the presence or absence of various pathway inhibitors. AVP stimulation of V1Rs leads to the phosphorylation of several kinases, an increase in DNA synthesis, a progression through the S and G2–M phases of the cell cycle, and an increase in cell proliferation. The mediators of the mitogenic action of V1R activation included calcium mobilization, coupling to a Gq protein, and the simultaneous and parallel activation of several kinases, mainly calcium/calmodulin-dependent kinase II, phosphatidylinositol 3 kinase, protein kinase C, and p42/p44 mitogen-activated protein kinase.

Damage by Dichlorvos of Human Lymphocyte DNA

1980 ◽  
Vol 66 (4) ◽  
pp. 425-430 ◽  
Author(s):  
Paolo Perocco ◽  
Angela Fini
Keyword(s):  
Dna Synthesis ◽  
Human Lymphocyte ◽  
Tritiated Thymidine ◽  
Human Lymphocytes ◽  
Ultraviolet Rays ◽  
Thymidine Uptake ◽  
Short Term ◽  
In Vitro System ◽  
Tritiated Thymidine Uptake

The action of dichlorvos (2.2-dichlorovinyldimethyl phosphate) was studied with a short-term in vitro system which utilizes human lymphocytes. The parameters studied were the action exerted by the pesticide on scheduled (semiconservative) and unscheduled (reparative) DNA synthesis measured as tritiated thymidine uptake. The results obtained show that dichlorvos affects semiconservative DNA synthesis, damages human lymphocyte DNA inducing low reparative synthesis, and interferes with DNA repair processes after damage exerted by ultraviolet rays.

scholarly journals SYNTHESIS OF DEOXYRIBONUCLEIC ACID BY MICRO- AND MACRONUCLEI OF TETRAHYMENA PYRIFORMIS

1962 ◽  
Vol 13 (2) ◽  
pp. 193-203 ◽  
Author(s):  
Barbara B. McDonald
Keyword(s):  
Dna Synthesis ◽  
Generation Time ◽  
Deoxyribonucleic Acid ◽  
Tritiated Thymidine ◽  
Tetrahymena Pyriformis ◽  
Type Ii ◽  
Total Period ◽  
Daughter Cells ◽  
Generation Times ◽  
The Times

Evidence as to the times of DNA synthesis in micronucleate Tetrahymena pyriformis (mating type II, variety 1) has been obtained by briefly exposing individuals of different ages to tritiated thymidine, returning them to non-radioactive medium, fixing at division, and preparing autoradiographs. A variable length of interphase, ranging from a few minutes to about 2 hours, has been found to precede the initiation of macronuclear DNA synthesis. Once begun, however, the period of synthesis appears to be similar in all cells, regardless of generation time, and has been estimated at 1 to 1½ hours. Under the conditions of these experiments, the time elapsing between the end of synthesis and subsequent division into daughter cells ranges from approximately 1½ to 2½ hours in generation times long enough to allow such variability. Division of the micronucleus occurs shortly before the cell begins to divide; its DNA synthesis starts immediately and continues after cell division for a total period estimated at about an hour.

Effect of inhibin on rat testicular desoxyribonucleic acid (DNA) synthesis in vivo and in vitro

1981 ◽  
Vol 98 (2) ◽  
pp. 312-320 ◽  
Author(s):  
P. Franchimont ◽  
F. Croze ◽  
A. Demoulin ◽  
R. Bologne ◽  
J. Hustin
Keyword(s):  
Dna Synthesis ◽  
Thymidine Incorporation ◽  
Specific Activity ◽  
Tritiated Thymidine ◽  
Biological Properties ◽  
Rete Testis ◽  
Thymidine Uptake ◽  
Adult Rats

Abstract. When injected in vivo 3 h before sacrifice or when incubated in vitro with testicular fragments for 3 h, tritiated thymidine, a reliable index of DNA synthesis and of mitotic activity, was incorporated into the DNA of differentiated spermatogonia, as shown by autohistoradiography. The maximum DNA specific activity was obtained in pubertal rats aged 42 days, weight 150 g. Two preparations of inhibin extracted from ram rete testis fluid (RTF) of different molecular weight (> 10 000 for RTF1 and < 5000 for RTF3) but which possess the same biological properties were investigated for their effect on thymidine uptake in vivo and in vitro. In vivo both preparations specifically inhibited tritiated thymidine incorporation into testicular DNA of pubertal animals (42 days). No change in thymidine uptake into hepatic DNA was observed. Tritiated thymidine incorporation into testicular DNA was lower in normal adult rats and in hypophysectomized pubertal animals. RTF1 and RTF3 did not affect thymidine incorporation in either case. The reasons for this lack of effect are discussed. In vitro, both preparations induced a dose-dependent decrease in DNA synthesis in testis fragments from rats aged 42 and 49 days. The preparations lost their in vivo and in vitro inhibitory effects when denatured by heating and trypsin digestion. The inhibin preparations probably reduced testicular DNA synthesis and spermatogonial multiplication by reducing FSH secretion in vivo but also had a direct effect on the germ cells as shown by the in vitro experiments. These in vivo and in vitro actions of inhibin preparations are similar to those of the testicular chalones. The relationship which might exist between inhibin and the chalones is discussed.

A STUDY OF BLASTOCYSTS DURING DELAY AND SUBSEQUENT IMPLANTATION IN LACTATING MICE

1968 ◽  
Vol 42 (3) ◽  
pp. 453-463 ◽  
Author(s):  
ANNE McLAREN
Keyword(s):  
Dna Synthesis ◽  
Thymidine Incorporation ◽  
Tritiated Thymidine ◽  
Uterine Horn ◽  
Uterine Epithelium ◽  
Serial Sections ◽  
Uterine Lumen ◽  
Fresh State

SUMMARY Blastocysts were studied on the 5th and 8th day of pregnancy in lactating mice, in the fresh state, flushed from the uterus, in squash preparations and in serial sections. At the earlier period some mitosis was observed. Tritiated thymidine incorporation studies gave some evidence of DNA synthesis on the 5th and 6th days of pregnancy. By the 8th day the blastocysts were longer, contained more cells, and mitosis had ceased. They were located at the anti-mesometrial end of the uterine lumen, closely apposed to the uterine epithelium, and with their long axes parallel to the long axis of the uterine horn. Implantation could be induced, either by the removal of the litter, or by the injection of an appropriate dose of oestrogen on the 5th or 7th (but not the 4th) day of pregnancy. Both treatments were followed by the appearance of W-bodies in the neighbourhood of the blastocysts, the disappearance of the shed zonae, and the appearance of Pontamine Blue reactivity, oedema of the uterine stroma and formation of the primary decidual zone, in that order.

scholarly journals Dem Anfang auf der Spur — die Suche nach DNA-Replikationsursprüngen

BIOspektrum ◽  
2021 ◽  
Vol 27 (3) ◽  
pp. 246-249
Author(s):  
Elisabeth Kruse ◽  
Stephan Hamperl
Keyword(s):  
Cell Division ◽  
Dna Synthesis ◽  
Genomic Dna ◽  
Genetic Material ◽  
Uniform Method ◽  
Replication Origins ◽  
Daughter Cells ◽  
Origins Of Replication ◽  
Mammalian Genomes ◽  
Comprehensive Manner

AbstractTimely and accurate duplication of DNA prior to cell division is a prerequisite for propagation of the genetic material to both daughter cells. DNA synthesis initiates at discrete sites, termed replication origins, and proceeds in a bidirectional manner until all genomic DNA is replicated. Despite the fundamental nature of these events, a uniform method that identifies origins of replication in a comprehensive manner is still missing. Here, we present currently available and discuss new approaches to map replication origins in mammalian genomes.

The development of the tectum in Xenopus laevis: an autoradiographic study

Development ◽  
1972 ◽  
Vol 28 (1) ◽  
pp. 87-115
Author(s):  
K. Straznicky ◽  
R. M. Gaze
Keyword(s):  
Xenopus Laevis ◽  
Dna Synthesis ◽  
Optic Tectum ◽  
Tritiated Thymidine ◽  
Dorsal Surface ◽  
Autoradiographic Study ◽  
Cell Type ◽  
Pole Cells ◽  
Serial Addition ◽  
The Times

The development of the optic tectum in Xenopus laevis has been studied by the use of autoradiography with tritiated thymidine. The first part of the adult tectum to form is the rostroventral pole; cells in this position undergo their final DNA synthesis between stages 35 and 45 or shortly thereafter. Next, the cells comprising the ventrolateral border of the tectum form. These cells undergo their final DNA synthesis at or shortly after stage 45. Finally the cells comprising the dorsal surface of the adult tectum form, mainly between stages 50–55. This part of the tectum originates from the serial addition of strips of cells medially, which displace the pre-existing tissue laterally and rostrally. The formation of the tectum is virtually complete by stage 58. The tectum in Xenopus thus forms in topographical order from rostroventral to caudo-medial. The distribution of labelled cells, several stages after the time of injection of isotope, indicates that, at any one time, a segment of tectum is forming which runs normal to the tectal surface and includes all layers from the ventricular layer out to the surface. In Xenopus, therefore, the times of origin of tectal cells appear to be related not to cell type or tectal layer but to the topographical position of the cells across the surface of the tectum.

Analysis of Hoxd-13 and Hoxd-11 misexpression in chick limb buds reveals that Hox genes affect both bone condensation and growth

Development ◽  
1997 ◽  
Vol 124 (3) ◽  
pp. 627-636 ◽  
Author(s):  
D.J. Goff ◽  
C.J. Tabin
Keyword(s):  
Growth Phase ◽  
Target Genes ◽  
Hox Genes ◽  
Bone Development ◽  
Tritiated Thymidine ◽  
Retroviral Vectors ◽  
Dominant Negative ◽  
Thymidine Uptake ◽  
Growth Promoters ◽  
Proliferative Zone

Hox genes are important regulators of limb pattern in vertebrate development. Misexpression of Hox genes in chicks using retroviral vectors provides an opportunity to analyze gain-of-function phenotypes and to assess their modes of action. Here we report the misexpression phenotype for Hoxd-13 and compare it to the misexpression phenotype of Hoxd-11. Hoxd-13 misexpression in the hindlimb results in a shortening of the long bones, including the femur, the tibia, the fibula and the tarsometatarsals. Mutations in an alanine repeat region in the N-terminus of Hoxd-13 have recently been implicated in human synpolydactyly (Muragaki, Y., Mundlos, S., Upton, J. and Olsen, B. R. (1996) Science 272, 548–551). N-terminal truncations of Hoxd-13 which lack this repeat were constructed and were found to produce a similar, although slightly milder, misexpression phenotype than the full-length Hoxd-13. The stage of bone development regulated by Hox genes has not previously been examined. The changes in bone lengths caused by Hoxd-13 misexpression are late phenotypes that first become apparent during the growth phase of the bones. Analysis of tritiated thymidine uptake by the tibia and fibula demonstrates that Hox genes can pattern the limb skeleton by regulating the rates of cell division in the proliferative zone of growing cartilage. Hoxd-11, in contrast to Hoxd-13, acts both at the initial cartilage condensation phase in the foot and during the later growth phase in the lower leg. Ectopic Hoxd-13 appears to act in a dominant negative manner in regions where it is not normally expressed. We propose a model in which all Hox genes are growth promoters, regulating the expression of the same target genes, with some Hox genes being more effective promoters of growth than other Hox genes. According to this model, the overall rate of growth in a given region is the result of the combined action of all of the Hox genes expressed in that region competing for the same target genes.

Interleukin 6 stimulates growth of vascular smooth muscle cells in a PDGF-dependent manner

1991 ◽  
Vol 260 (5) ◽  
pp. H1713-H1717 ◽  
Author(s):  
U. Ikeda ◽  
M. Ikeda ◽  
T. Oohara ◽  
A. Oguchi ◽  
T. Kamitani ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Interleukin 6 ◽  
Thymidine Incorporation ◽  
Tritiated Thymidine ◽  
Muscle Cells ◽  
Thymidine Uptake ◽  
Dependent Manner

We have investigated the effect of interleukin 6 (IL-6) on the growth of vascular smooth muscle cells (VSMC) isolated from rat aortas. Murine recombinant IL-6 significantly increased the number of VSMC and stimulated tritiated thymidine incorporation into VSMC in a dose-dependent manner. The IL-6-induced thymidine incorporation into VSMC was totally inhibited by the Ca2+ channel blocker verapamil; however, IL-6 showed no effects on the intracellular Ca2+ level ([Ca2+]i) in VSMC. Antibody against platelet-derived growth factor (PDGF) also totally inhibited the IL-6-induced thymidine uptake. PDGF caused a significant increase in the [Ca2+]i, which was totally inhibited by verapamil. IL-6 mRNA was not detected in unstimulated “quiescent” VSMC, but its expression was stimulated by exposure of VSMC to 10% fetal bovine serum. Immunohistochemical study using anti-PDGF antibody showed that IL-6 stimulated PDGF production in VSMC. These results support the premise that IL-6 is released by VSMC in an autocrine manner and promotes the growth of VSMC via induction of endogenous PDGF production.

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