The mechanism for induction of tumors by estrogens is still unresolved. Neoplastic transformation of Syrian hamster em bryo fibroblasts by diethylstilbestrol (DES) suggests that estab lished principles of chemical carcinogenesis may be involved. The Syrian hamster embryo fibroblast cells provide a system in which now the question can be asked whether the metabolic activation of DES is a prerequ...

Photooxidized tryptophan (TRP) in tissue culture medium elicits a transient cytochrome P450 (CYP1) induction response in cultured cells. We show here that exposure of TRP to window sunlight (aTRP) greatly increased the potency, efficacy, and duration of CYP1A induction by TRP in primary chick embryo hepatocytes and in vivo. Aqueous TRP exposed to sunlight for 7 days exhibited a 100-fold or grea...

The possible involvement of Ca(2+)-mediated signaling in the induction/regulation of somatic embryogenesis from pro-embryogenic cells of sandalwood (Santalum album) has been investigated. (45)Ca(2+)-uptake studies and fura-2 fluorescence ratio photometry were used to measure changes in [Ca(2+)](cyt) of pro-embryogenic cells in response to culture conditions conducive for embryo development. San...

background: many studies reported that follicle size has an essential role in developmental potential of oocytes. also, the brilliant cresyl blue (bcb) test is one of the most important criteria in selection of more competent oocytes. objective: selection of developmentally competent bovine oocytes. materials and methods: a total of 1730 bovine cumulus oocyte complexes (cocs) were recovered fro...

Apoptotic and Epigenetic Induction of Embryo Failure Following Somatic Cell Nuclear Transfer

PURPOSE To investigate the regulation of visual pigment expression in chick embryo photoreceptor cells by ciliary neurotrophic factor (CNTF), and by the protein kinase inhibitor staurosporine. METHODS Embryonic day (ED) 8 chick embryo retinal cells were dissociated and cultured at low densities for 3 days, either in control medium or in medium supplemented with CNTF or staurosporine. The cult...