Members of the DAZ gene family encode RNA-binding proteins and have been shown to play a pivotal role in gametogenesis. In Xenopus, a DAZ-like gene encodes an RNA component of the germ plasm. We have identified a zebrafish DAZ homologue, zDazl. zDazl mRNA was expressed in gonads of both sexes. In ovary, it was localized in the cortex of oocytes. At the onset of embryogenesis, maternal zDazl mRN...

Xenopus eggs, artificially fertilized, were prevented from undergoing equilibrium rotation by incubation in medium containing ficoll. Three orientations were selected: normal, with animal pole uppermost; inverted, with vegetal pole away from gravity; and an off-axis orientation, with embryos tilted approximately 90 degrees from the animal-vegetal axis. At blastula stage 8, cells forming the bla...

β-catenin is thought to mediate cell fate specification events by localizing to the nucleus where it modulates gene expression. To ask whether β-catenin is involved in cell fate specification during sea urchin embryogenesis, we analyzed the distribution of nuclear β-catenin in both normal and experimentally manipulated embryos. In unperturbed embryos, β-catenin accumulates in nuclei that includ...

The amphibian embryo develops into the three germ layers in a predictable fashion, the pigmented animal pole forming the ectoderm, the yolky vegetal pole forming the endoderm and the mesoderm developing from an annulus at the equator. Mesoderm formation is believed to require a TGF-β family signal originating from vegetal cells because a truncated dominant negative activin receptor, promiscuous...

In conservation agriculture, the no-tillage cultivation system and retention of permanent vegetal cover are crucial to control soil erosion by water. This paper analyses maize under no-tillage, with particular reference effect produced on when weed is performed a hand tool (machete), which disturbs surface soil, behavior in these circumstances. The study area located humid tropical mountains no...