During the period of mitosis, two surface contraction waves (SCWs) progress from the animal to vegetal poles of the Xenopus egg. It has been shown that these SCWs occur in parallel with the activation of MPF and with its subsequent inactivation in the animal and vegetal hemispheres, suggesting that they are responses to propagated waves of MPF activity across the egg. We have analysed the mecha...

A main achievement of gastrulation is the movement of the endoderm and mesoderm from the surface of the embryo to the interior. Despite its fundamental importance, this internalization process is not well understood in amphibians. We show that in Xenopus, an active distortion of the vegetal cell mass, vegetal rotation, leads to a dramatic expansion of the blastocoel floor and a concomitant turn...

Aphidicolin, an inhibitor of DNA polymerase alpha, blocks DNA synthesis and cell division in sea urchin embryos. The effects of this inhibition appear to be stage dependent. Blastulae treated with aphidicolin before the thickening of the vegetal plate undergo developmental arrest prior to gastrulation. The extent of inhibition of DNA synthesis varies from 60 to 93% in these embryos. However, wh...

The developmental potential of different blastomeres of the sea urchin embryo was re-examined. We have employed a new method to isolate substantial numbers of different kinds of blastomeres from 16-cell-stage embryos, and we have used newly available molecular markers to analyze possible vegetal differentiation. We have found that, while isolated mesomere pairs behave according to the classical...

VegT is a T-box transcription factor whose mRNA is synthesized during oogenesis and localized in the vegetal hemisphere of the egg and early embryo. We show that maternally expressed VegT controls the pattern of primary germ layer specification in Xenopus embryos. Reduction of the maternal store completely alters the fates of different regions of the blastula so that animal cell fate is changed...

The aim of the study was to analyse polyphenols compounds from vegetal product Holoschoeni rhizome and its antioxidant capacity in order to justify traditional therapeutic using (livery protect effect). The separation, identification and quantification of polyphenols compounds were made through High performance of liquid chromatography (HPLC), standardized method according USP30-NF25 Monograph....

Departamento de Biologı́a Molecular de Plantas, Instituto de Biotecnologı́a, Universidad Nacional Autónoma de México, Apartado Postal 510–3, Cuernavaca Morelos 62271, México (L.C., F.S., C.Q.); Biology Department, Morrill Science Center, University of Massachusetts, Box 35810, Amherst, Massachusetts 01003–5810 (T.L.H.-C., J.G.K., P.K.H.); Instituto Gulbenkian de Ciência, P–2780–156 Oeiras, Portug...

We found that there are two major pathways by which RNAs are localized at the vegetal cortex during oogenesis of Xenopus laevis. One of these, through which Xlsirts, Xcat2 and Xwnt11 are localized, involves transport during stages 1 and 2 of oogenesis via a region of the mitochondrial cloud that we call the message transport organizer or METRO. This pathway involved three steps, transport of RN...