The molecular basis for the inhibition of the Ca2+,Mg2+-dependent endonuclease resulting from the formation of poly(adenosine diphosphate ribose) (ADP-Rib) was studies in a simplified system containing purified rat liver or bull semen endonuclease, purified rat liver poly(ADP-Rib) synthetase, [3H]NAD+, and DNA. Poly-(adp-rib) synthetase activity was stimulated when Ca2+, Mg2+-dependent endonuclease was added to the reaction mixture in place of histones, suggesting that the endonuclease can act as an acceptor for ADP-Rib. Evidence was presented to show that the ADP-Rib moiety of [3H]NAD+ was incorporated in the endonuclease fraction. The [3H]ADP-Rib bound to the endonuclease was in the form of monomers and oligomers and not long chain polymers. The present results suggest that the Ca2+,Mg2+-dependent endonuclease was ADP-ribosylated when the endonuclease was incubated with poly(ADP-Rib) synthetase and NAD+.

Adenosine Diphosphate↗

PubMed1975

Effect of estradiol on the early incorporation of (3H) thymidine into uterine DNA on immature mouse.

The incorporation of [3H]thymidine into uterine DNA was markedly depressed within 10 to 30 minutes after intraperitoneal administration of 17beta-estradiol to immature mouse. Maximum inhibition occurred about 6 hours after the hormone was administered. Uterine DNA content and the amount of [3H]thymidine incorporated into the acid-soluble fraction was not affected during the period of hormone-induced inhibition. Moreover, the in vitro incorporation of [3H]thymidine by isolated estradiol-treated mouse uterus was blocked. In contrast to the uterus, 17beta-estradiol did not influence the incorporation of thymidine into mouse liver DNA. Evidence is presented to show that the incorporation of thymidine into uterine DNA was blocked initially by 17beta-estradiol.

Animals↗

PubMed1975

Endonuclease activity in bull semen, testis and accessory sex organs.

Explore the source record for details and available documents.

Animals↗

PubMed1975

Poly (adnenosine diphosphoribose) synthase activity of isolated nuclei of normal and leukemic leukocytes.

Poly(adenosine diphosphoribose) (ADPR) synthase activities of nuclei isolated from normal human and leukemic leukocytes were assayed by incubation with radioactive NAD+. The synthase activity of leukemic leukocyte nuclei was significantly higher than that of normal leukocyte nuclei. The average length of polymers formed by isolated leukemic nuclei under the prescribed experimental condition ranged from 3.1 to 5.3 ADPR residues per chain, while those produced by normal leukocytes nuclei was 1.7 and 2.6 residues per chain. Isolated leukemic and normal leukocyte nuclei were incubated with and without NAD+ and the ability to carry out DNA synthesis was measured. The endogenous DNA synthesis of NAD-treated and untreated nuclei was the same. This finding parallels the result obtained with Novikoff hepatoma cell nuclei and differs from the observation with rat liver or testis nuclei.

Cell Nucleus↗

PubMed1975

Unusal signs and symptoms associated with oral contraceptive medication.

A review of medical literature concerning case history reports of adverse clinical manifestations of hormonal contraceptives is presented. While extremely rare, these side-effects often present with obscure etiology, and the physician is cautioned to be aware of their occurrence.

Adolescent↗

PubMed1974