In eggs of Xenopus laevis, dorsal development is activated on the future dorsal side by cortical rotation, after fertilization. The immediate effect of cortical rotation is probably the transport of a dorsal determinant from the vegetal pole to the equatorial region on the future dorsal side. However, the identity and action of the dorsal determinant remain problematic. In the present experimen...

A first natural idea to extend Maskin monotonicity into a property that would be applicable on any domain of individual choice functions is to use Bernheim and Rangel’s (2009) extended revealed preference, as defined at the beginning of Section 4 of the main paper. For each individual i, each state θ, and each option x, the lower contour set LCi(x, θ) of x given θ is now the set of options y su...

We study the repeated implementation of social choice functions in environments with complete information and changing preferences. We define dynamic monotonicity, a natural but nontrivial dynamic extension of Maskin monotonicity, and show that it is necessary and almost sufficient for repeated Nash implementation, regardless of whether the horizon is finite or infinite and whether the discount...

The inwardly-rectifying potassium channel subunit Kir5.1 selectively co-assembles with members of the Kir4.0 subfamily to form novel pH-sensitive heteromeric channels with unique single channel properties. In this study, we have cloned orthologs of Kir4.1 and Kir5.1 from the genome of the amphibian, Xenopus tropicalis (Xt). Heteromeric XtKir4.1/XtKir5.1 channels exhibit similar macroscopic curr...

Introduction Experimental embryology and mesoderm induction The three-signal model of mesoderm formation Mesoderm-inducing factors Mesoderm-inducing factors as growth factors Xenopus embryos contain TGF-fi-like molecules Xenopus embryos contain FGF Elimination of inducing factors from Xenopus embryos Mesoderm-inducing factors and pattern formation Thresholds Mesoderm induction, gastrulation and...

We previously characterized major components of mitotic chromosomes assembled in Xenopus laevis egg extracts and collectively referred to them as Xenopus chromosome-associated polypeptides (XCAPs). They included five subunits of the condensin complex essential for chromosome condensation. In an effort to identify novel proteins involved in this process, we have isolated XCAP-F and found it to b...

Xenbase (http://www.xenbase.org) is a model organism database that provides genomic, molecular, cellular and developmental biology content to biomedical researchers working with the frog, Xenopus and Xenopus data to workers using other model organisms. As an amphibian Xenopus serves as a useful evolutionary bridge between invertebrates and more complex vertebrates such as birds and mammals. Xen...

We have determined the complete nucleotide sequence of Xenopus laevis 28S rDNA (4110 bp). In order to locate evolutionarily conserved regions within rDNA, we compared the Xenopus 28S sequence to homologous rDNA sequences from yeast, Physarum, and E. coli. Numerous regions of sequence homology are dispersed throughout the entire length of rDNA from all four organisms. These conserved regions hav...

To study the regulation of AUUUA-mediated RNA deadenylation and destabilization during Xenopus early development, we microinjected chimeric mRNAs containing Xenopus or mammalian 3' untranslated region (3'-UTR) sequences into Xenopus oocytes, mature eggs, or fertilized embryos. We found that the AU-rich elements (ARE) of Xenopus c-myc II and the human granulocyte-macrophage colony-stimulating fa...