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The first chordates appear in the fossil record at the time of the Cambrian explosion, nearly 550 million years ago. The modern ascidian tadpole represents a plausible approximation to these ancestral chordates. To illuminate the origins of chordate and vertebrates, we generated a draft of the protein-coding portion of the genome of the most studied(More)
Using an expression cloning strategy that relies on a functional assay, we have cloned a novel Xenopus homeobox-containing gene, Siamois. Embryos injected in a ventral-vegetal blastomere with as little as 5 pg of Siamois mRNA develop a complete secondary axis, but the progeny of the injected cells do not participate in the secondary axis formation. In(More)
This study reports a longitudinal investigation of French 2nd graders' acquisition of single-digit multiplication skill. Speed, accuracy, and strategy use were assessed 3 times within the year when children learned multiplication. The data showed that improvements in speed and accuracy that generally accompany learning can reflect at least 4 types of(More)
The choice/no-choice method provides a means of obtaining unbiased estimates of the performance characteristics of strategies. The three experiments in the study illustrate the method's usefulness for testing predictions of alternative models of strategy choice. The experiments focused on 20- and 70-year-olds' choices among mental calculation, use of a(More)
Although the proteins that read the gene regulatory code, transcription factors (TFs), have been largely identified, it is not well known which sequences TFs can recognize. We have analyzed the sequence-specific binding of human TFs using high-throughput SELEX and ChIP sequencing. A total of 830 binding profiles were obtained, describing 239 distinctly(More)
Neural induction constitutes the first step in the generation of the vertebrate nervous system from embryonic ectoderm. Work with Xenopus ectodermal explants has suggested that epidermis is induced by BMP signals, whereas neural fates arise by default following BMP inhibition. In amniotes and ascidians, however, BMP inhibition does not appear to be(More)
Participants were asked to verify if complex additions were smaller than 100 or not. Two hundred and forty arithmetic problems were presented, with half the problems being small-split problems (i.e. proposed sums were 2 or 5% away from 100) and half being large-split problems (i.e. proposed sums were 10 or 15% away from 100). Behavioral and ERPs data(More)
BACKGROUND The draft genome sequence of the ascidian Ciona intestinalis, along with associated gene models, has been a valuable research resource. However, recently accumulated expressed sequence tag (EST)/cDNA data have revealed numerous inconsistencies with the gene models due in part to intrinsic limitations in gene prediction programs and in part to the(More)
With little more than 330 cells, two thirds within the sensory vesicle, the CNS of the tadpole larva of the ascidian Ciona intestinalis provides us with a chordate nervous system in miniature. Neurulation, neurogenesis and its genetic bases, as well as the gene expression territories of this tiny constituency of cells all follow a chordate plan, giving rise(More)
In the present study, we examined the conditions that favor the plausibility judgment strategy over the retrieval strategy when we verify some statements. In particular, we examined the effect of odd-even status of numbers on subjects' verification of single-digit arithmetic problems. In Experiment 1, we explored how factors such as problem difficulty and(More)