scholarly journals Reduction of Chloroplast DNA Content in Solanum nigrum Suspension Cells by Treatment with Chloroplast DNA Synthesis Inhibitors

1990 ◽  
Vol 94 (3) ◽  
pp. 1477-1483 ◽  
Author(s):  
Jingsong Ye ◽  
Richard T. Sayre
Keyword(s):  
Dna Synthesis ◽  
Chloroplast Dna ◽  
Dna Content ◽  
Solanum Nigrum ◽  
Suspension Cells ◽  
Dna Synthesis Inhibitors

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.

Effect of thyroparathyroidectomy on the activities of thymidylate synthetase and thymidine kinase during liver regeneration after partial hepatectomy

1987 ◽  
Vol 72 (4) ◽  
pp. 455-461 ◽  
Author(s):  
Rieko Nakata ◽  
Ikuyo Tsukamoto ◽  
Masamitsu Miyoshi ◽  
Shosuke Kojo
Keyword(s):  
Dna Synthesis ◽  
Liver Regeneration ◽  
Time Dependence ◽  
Thymidine Kinase ◽  
Partial Hepatectomy ◽  
Dna Content ◽  
Thymidylate Synthetase ◽  
High Dose ◽  
Regenerating Liver ◽  
Relative Contribution

1. Thyroparathyroidectomy (TPTX) carried out at 72 h before partial hepatectomy (PH) reduced the induction of hepatic thymidylate synthetase (TS) and thymidine kinase (TK), which are rate-determining enzymes in DNA synthesis, at 24 h after PH. 2. When TPTX was carried out at 24 h before PH, TK activity at 24 h after PH was not reduced at all, yet TS activity was reduced significantly. Thus the effect of TPTX differed in time dependence between TS and TK. 3. The depression of TK activity in rats which were subjected to TPTX at 72 h before PH, was recovered by Ca2+ supplementation. This result demonstrated that the rise of TK activity in regenerating liver is regulated by plasma Ca2+. 4. Since a high dose of tri-iodothyronine (T3) was required to cause elevation of the activities of these enzymes and DNA content in 24 h-regenerating liver of TPTX rats, the relative contribution of T3 to liver regeneration may be small.

Chloroplast DNA content increases with nuclear ploidy in Chlamydomonas

1977 ◽  
Vol 157 (1) ◽  
pp. 11-15 ◽  
Author(s):  
Malcolm S. Whiteway ◽  
Robert W. Lee
Keyword(s):  
Chloroplast Dna ◽  
Dna Content ◽  
Nuclear Ploidy

Cytoplasmic DNA and basic protein synthesis in Megalobatrachus davidianus oocytes

Development ◽  
1971 ◽  
Vol 26 (2) ◽  
pp. 271-283
Author(s):  
Y. C. Kong ◽  
I. F. Lau ◽  
W. L. Lam ◽  
C. M. Choy
Keyword(s):  
Protein Synthesis ◽  
Dna Synthesis ◽  
Dose Response ◽  
Dna Content ◽  
Active Site ◽  
Basic Protein ◽  
Basic Proteins ◽  
Biochemical Event ◽  
Cytoplasmic Dna

Mature Megalobatrachus oocytes contain 43 µg DNA per oocyte, as compared with 250 pg DNA in a hepatocyte of the same animal. Megalobatrachus oocytes respond to CdR treatment by an increased incorporation of [3H]lysine into basic proteins associated with ooplasmic particles, with an optimal CdR concentration at 2 mM. The nucleolus is the most active site of [3H]lysine incorporation. It is suggested that CdR-stimulated basic protein synthesis is a common biochemical event during amphibian oogenesis. The dose response to CdR treatment may be a function of the c-DNA content or c-DNA synthesis potential in the ooplasm.

scholarly journals A RADIOAUTOGRAPHIC STUDY WITH H3-THYMIDINE ON ADRENAL MEDULLA NUCLEI OF RATS INTERMITTENTLY EXPOSED TO COLD

1966 ◽  
Vol 28 (1) ◽  
pp. 9-19 ◽  
Author(s):  
Maria Pia Viola-Magni
Keyword(s):  
Cell Division ◽  
Dna Synthesis ◽  
Adrenal Medulla ◽  
Cold Exposure ◽  
Dna Content ◽  
Room Temperature ◽  
Marked Variation ◽  
Considerable Decrease ◽  
The Third

A considerable decrease (24 to 40%) of DNA content per nucleus previously observed in the adrenal medulla of rats exposed intermittently to cold is followed by restoration to normal and supranormal values. This phenomenon has now been studied by use of H3-thymidine, which was given to normal rats, to rats exposed to cold, and to animals brought to room temperature after cold exposure. In the first two conditions, no significant labeling of nuclei was observed. In the third, labeling took place clearly in the 1st 3 days. The grain counts showed that the early labeled nuclei had more grains than those labeled later, indicating differences in the rate of DNA synthesis. A statistically significant correlation was found, on the same nuclei, between amount of Feulgen dye and number of grains. It is concluded that net synthesis of DNA takes place in the phase of recovery from cold. This fact is not related to cell division, as no mitoses could ever be detected, but rather to the cold-induced loss of DNA. Clear demonstration is thus given of a marked variation in the amount of DNA per nucleus in relation to the functional conditions of adrenal medulla cells.

Ontogeny of cell proliferation and DNA synthesis in rat colon: role of glucocorticoids

1983 ◽  
Vol 244 (5) ◽  
pp. G469-G474 ◽  
Author(s):  
J. P. Buts ◽  
R. De Meyer ◽  
J. Kolanowski
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Dna Synthesis ◽  
Mitotic Index ◽  
Dna Content ◽  
Thymidine Incorporation ◽  
Rat Colon ◽  
Epithelial Cell Proliferation ◽  
New Findings

This study was undertaken to determine whether the rat colon exhibits ontogenic changes in epithelial cell proliferation and DNA synthesis during growth. DNA synthesis was measured at intervals after birth in four colonic segments by the incorporation rates of [3H]thymidine. The labeled crypt cell index was determined by radioautography. New findings from our study are that 1) in each colonic segment of suckling rats, [3H]thymidine incorporation rate overshot the adult levels (49-119%) with a peak occurring at day 14 postpartum, 2) between days 14 and 20, the incorporation rates declined sharply to adult values and remained thereafter unchanged until adulthood; during the same period, the labeled and mitotic index decreased, respectively, from 52 to 19% and from 3.58 to 1.43%, 3) the decrease in DNA synthesis and in cell proliferation rates was concomitant with an upsurge in plasma total corticosterone initiated on day 14, and 4) treatment of 10-day-old sucklings with physiological doses of hydrocortisone for 4 consecutive days significantly depressed (P less than 0.01) colonic DNA content and DNA synthesis rates to levels about 45-67% of the control values. These data indicate that growth of the colon may be under the control of glucocorticoid secretion at the weaning period.

scholarly journals DNA CONTENT OF PLACENTAL NUCLEI

1962 ◽  
Vol 13 (2) ◽  
pp. 183-191 ◽  
Author(s):  
Michael Galton
Keyword(s):  
Cell Proliferation ◽  
Dna Synthesis ◽  
Mitotic Activity ◽  
Dna Content ◽  
Reproductive Capacity ◽  
Interphase Nuclei ◽  
Daughter Cells ◽  
Reproductive Ability ◽  
Dna Values ◽  
Rapid Accumulation

The DNA content of individual nuclei in four immature human placentas was determined by microspectrophotometric analysis of Feulgen-stained sections. The absence of mitosis in the syncytiotrophoblast, taken together with the finding of a diploid unimodal distribution, at a time of rapid placental growth, indicated that the syncytiotrophoblast possessed little or no intrinsic reproductive capacity. In contrast, the cytotrophoblast displayed considerable mitotic activity and was found to contain a high proportion of nuclei with DNA values in excess of the diploid amount, corresponding to DNA synthesis in interphase nuclei preparatory to division. From the complementary behavior of the two layers of trophoblast, with respect to evidence of reproductive ability, it is concluded that the rapid accumulation of nuclei in the syncytiotrophoblast, during the early development of the placenta, is accounted for by cell proliferation within the cytotrophoblast followed by alignment and coalescence of some daughter cells in the syncytiotrophoblast.

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