The NADH-dependent stearoyl CoA desaturase of hepatic microsomes (EC 1.14.99.5) is an enzyme system consisting of cytochrome b5 reductase (EC 1.6.2.2), cytochrome b5, and the terminal desaturase. We have developed a simple method for routine assay of the terminal enzyme based on complementation of the enzyme with chick embryo liver microsomes lacking desaturase activity. Desaturation of [1-14C]...

Red cells are required not only for adult well-being but also for survival and growth of the mammalian embryo beyond early postimplantation stages of development. The embryo's first "primitive" erythroid cells, derived from a transient wave of committed progenitors, emerge from the yolk sac as immature precursors and differentiate as a semisynchronous cohort in the bloodstream. Surprisingly, th...

An enzyme involved in the metabolic activation of thalidomide has been investigated using embryo fibroblast proliferation as a marker. Thalidomide (30 microM) induced-suppression of embryo fibroblast proliferation was detected in the presence of liver microsomes from rabbit but not from mouse. The addition of a selective inhibitor of CYP1A, alpha-naphthoflavone (4 microM), or furafylline (4 mic...

The potency of N-methylprotoporphyrin IX (N-methylPP) as a ferrochelatase (FC) inhibitor has been previously studied using crude chick embryo liver FC preparations. However, interactions between N-methylprotoporphyrin IX (N-methylPP) and impurities in the enzyme preparation may have compromised the results. The first objective of this study was to compare the potency of N-methylPP as an inhibit...

T H E investigations of Dalton (1937) and of Lee (1951) have shown that glycogen appears in the liver of the chicken embryo at 7-8 days' incubation and before the formation of insulin by the islets of Langerhans at 11-12 days (Potvin & Aron, 1927). Further, Dalton (1937) has shown that when livers of embryos of 3 days' incubation were transplanted on to the chorio-allantoic membrane of 11-13day...

The RNA-P and DNA-P content of the nucleus and the RNA-P content of the whole cell of the livers of 8- to 20-day chick embryos and of adult fowls have been determined. The DNA-P content of the liver nuclei was slightly higher in the 8- and 10-day embryo than in all the other stages examined. A significant decrease in the RNA content of the cell occurred during embryonic development. The RNA con...

The RNA-P and DNA-P content of the nucleus and the RNA-P content of the whole cell of the livers of 8to 20-day chick embryos and of adult fowls have been determined. The DNA-P content of the liver nuclei was slightly higher in the 8and 10-day embryo than in all the other stages examined. A significant decrease in the RNA content of the cell occurred during embryonic development. The RNA content...

It is now accepted from studies in animal models that hematopoietic stem cells emerge in the para-aortic mesoderm-derived aorta-gonad-mesonephros region of the vertebrate embryo. We have previously identified the equivalent primitive hematogenous territory in the 4- to 6-week human embryo, under the form of CD34(+)CD45(+)Lin- high proliferative potential hematopoietic cells clustered on the ven...

background: successful embryo transfer (et) technique is a fateful step of all efforts to achieve live births from in vitro produced embryos in assisted reproductive techniques or in knockout, transgenic or cloned animal projects. small reproductive tract of mice and limitation of current techniques may not well satisfy the requirements for mass production of genetically modified mice. genetic ...