The appearance of the embryonic shield, a slight thickening at the leading edge of the blastoderm during the formation of the germ ring, is one of the first signs of dorsoventral polarity in the zebrafish embryo. It has been proposed that the shield plays a role in fish embryo patterning similar to that attributed to the amphibian dorsal lip. In a recent study, we fate mapped many of the cells ...

The small intestine is probably the major site for the conversion of p-carotene into retinol ester (vitamin A ester)1 in the mammal (2-5), but other tissues are capable of catalyzing this cleavage reaction, e.g. the conversion takes place in viva after removal of the intestine (6) and of various other organs (6-9). Direct evidence for the participation of other tissues, however, is lacking. Alt...

Neuroblastoma is a solid tumor often diagnosed in childhood. While there have been intense efforts to develop a treatment for neuroblastoma, current therapies remain unsuccessful due to high rate of resistance and metastasis. Most cancers originate from a subset of self-renewing cells, primarily cancer stem cells (CSCs), which establish a tumor through continuous self-renewal and differentiatio...

Background: Prompt gamma neutron activation analysis (PGNAA) is known as a non-invasive technique capable of measuring elemental concentration in voluminous samples in a short period of time. Also it is a valuable diagnostic tool for total body elemental measurements. 252Cf and 241Am-Be sources which are usually used in this method, generate not only neutrons, but also emit high-energy and unwa...

We present a sensitive tracer method, suitable for in vivo human research, that uses beta-[(14)C]carotene coupled with accelerator mass spectrometry (AMS) detection. Using this approach, the concentration-time course of a physiological (306 microgram 200 nCi) oral dose of beta-[(14)C]carotene was determined for 209 days in plasma. Analytes included beta-[(14)C]carotene, [(14)C]retinyl esters, [...

PURPOSE Vitamin A is essential for vision. The key step in the vitamin A biosynthetic pathway is the oxidative cleavage of beta-carotene into retinal by the enzyme beta,beta-carotene-15,15'-monooxygenase (BCO). The purpose of the study was to investigate beta-carotene metabolism and its effects on BCO expression in the human retinal pigment epithelial (RPE) cell line D407. METHODS BCO mRNA an...

beta-carotene is an antioxidant molecule of commercial value that can be naturally produced by certain microalgae that mostly belong to the genus Dunaliella. So far, nitrogen starvation has been the most efficient condition for enhancing beta-carotene accumulation in Dunaliella. However, while nitrogen starvation promotes beta-carotene accumulation, the cells become non-viable; consequently und...

The endosperm of Golden Rice (Oryza sativa) is yellow due to the accumulation of beta-carotene (provitamin A) and xanthophylls. The product of the two carotenoid biosynthesis transgenes used in Golden Rice, phytoene synthase (PSY) and the bacterial carotene desaturase (CRTI), is lycopene, which has a red color. The absence of lycopene in Golden Rice shows that the pathway proceeds beyond the tr...

BACKGROUND Some of the main nutritional reasons for recommending a Mediterranean diet is to prevent metabolic diseases arising through free radical formation. A key constituent compound is beta-carotene which, amongst the carotenoids, displays the greatest provitamin A activity as well as possessing significant antioxidant properties. OBJECTIVES Principally, to determine the relationship betw...