Following fertilization of the egg of the sand dollar Echinarachnius parma, tritiated thymidine (H(3)TDR) 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 expos...

Autologous serum used in lymphocyte cultures in transformation studies for the examination of cell-mediated immunity in leprosy patients has been shown to contain substance(s) which depressed the 3H-thymidine incorporation into DNA in phytohemagglutinin (PHA) stimulation of leukocytes (4.27). Initial attempts at physical and chemical characterization of the serum factor have been made by Bulloc...

Normal polymorphonuclear neutrophils (PMNs) constitutively secrete a mediator designated granulocyte-derived factor (GDF) that can enhance the uptake of 3H-thymidine (3- to 20-fold) by the molt-3, CTV-1, and K562 leukemic cell lines in a dose-dependent manner. GDF is heat labile (56 degrees C for 30 minutes) and acid labile (pH 2.0) and is sensitive to treatment with bacterial protease type IV....

In this study, we describe the cloning and characterization of a proton-dependent, broadly selective nucleoside transporter from Caenorhabditis elegans. Recently, we constructed a broadly selective nucleoside transporter which accepts both purine and pyrimidine nucleosides. Based on these studies, we hypothesized that CNTs with novel substrate selectivities exist in nature and that a CNT homolo...

Cimicifugoside is a triterpenoid originating from the rhizomes of Cimicifuga simplex, and acts to inhibit the subcellular transport of nucleosides. Cimicifugoside, when used in combination with methotrexate, showed a cellspecific synergic effect on the promonocytic leukemia cell line U937, but not on the chronic myelogenetic leukemia cell line K562. Thymidine uptake was more severely inhibited ...