Maternal homozygosity for three independent mutant hecate alleles results in embryos with reduced expression of dorsal organizer genes and defects in the formation of dorsoanterior structures. A positional cloning approach identified all hecate mutations as stop codons affecting the same gene, revealing that hecate encodes the Glutamate receptor interacting protein 2a (Grip2a), a protein contai...

During the first cell cycle of the ascidian egg, two phases of ooplasmic segregation create distinct cytoplasmic domains that are crucial for later development. We recently defined a domain enriched in ER in the vegetal region of Phallusia mammillata eggs. To explore the possible physiological and developmental function of this ER domain, we here investigate its organization and fate by labelin...

The animal/vegetal (A/V) polarity of the typical amphibian egg is immediately recognizable by the distinct pigmentation differences between the darkly pigmented (animal) and lightly pigmented (vegetal) hemispheres. That polarity arises early in oogenesis. Prior to the vitellogenic period during which yolk platelets accumulate and the original (uniform) pigmentation pattern changes, a polarized ...

The ability of Aspergillus japonicus ATCC 20236 to colonize different synthetic materials (polyurethane foam, stainless steel sponge, vegetal fiber, pumice stones, zeolites, and foam glass) and to produce fructooligosaccharides (FOS) from sucrose (165 g/L) is described. Cells were immobilized in situ by absorption, through direct contact with the carrier particles at the beginning of fermentati...

The HE gene is the earliest strictly zygotic gene activated during sea urchin embryogenesis. It is transiently expressed in a radially symmetrical domain covering the animal-most two-thirds of the blastula. The border of this domain, which is orthogonal to the primordial animal-vegetal axis, is shifted towards the animal pole in Li+-treated embryos. Exogenous micromeres implanted at the animal ...

The fourth cleavage in sea urchin embryos is unequal and represents an initial step in cell differentiation: vegetal blastomeres divide to produce micromeres, which are precursors of the skeletogenic mesenchyme, and macromeres. The mitotic spindles of these unequally dividing cells are peripherally located and lie orthogonal to the vegetal pole plasma membrane; the aster of the micromere pole i...

Localization of mRNA is an important way of generating early asymmetries in the developing embryo. In Drosophila, Staufen is intimately involved in the localization of maternally inherited mRNAs critical for cell fate determination in the embryo. We show that double-stranded RNA-binding Staufen proteins are present in the oocytes of a vertebrate, Xenopus, and are localized to the vegetal cytopl...

Specification of the dorsoventral axis in Xenopus depends on rearrangements of the egg vegetal cortex following fertilization, concomitant with activation of Wnt/beta-catenin signaling. How these processes are tied together is not clear, but RNAs localized to the vegetal cortex during oogenesis are known to be essential. Despite their importance, few vegetally localized RNAs have been examined ...

The effect of removing parts of unfertilized and fertilized eggs of Dentalium has been studied. Up to 70 % of the volume of a 1st polar lobe can be removed from the vegetal side of both unfertilized and fertilized eggs, without influencing apical tuft formation. The post-trochal region is reduced. These eggs form a reduced polar lobe at first cleavage. After removal of more than 70 % of the vol...

cDNAs specific to vegetal poles of Xenopus gastrula embryos were used as a probe to screen a gastrula vegetal pole cDNA library. One of the novel clones isolated had an RNA expression pattern consistent with it being a component of germ plasm and it was thus named Xpat (Xenopus primordial germ cell associated transcript). The open reading frame encodes a 35 kDa protein with no clear homologies....