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The larval arms of echinoid plutei are used for locomotion and feeding. They are composed of internal calcite skeletal rods covered by an ectoderm layer bearing a ciliary band. Skeletogenesis includes an autonomous molecular differentiation program in primary mesenchyme cells (PMCs), initiated when PMCs leave the vegetal plate for the blastocoel, and a(More)
The direct-developing sea urchin species Heliocidaris erythrogramma has a radically modified ontogeny. Along with gains of novel features, its entire ectoderm has been reorganized, resulting in the apparent absence of a differentiated oral ectoderm, a major module present in the pluteus of indirect-developing species, such as H. tuberculata. The restoration(More)
Adult echinoderms possess a highly diverged, pentaradial body plan. Developmental mechanisms underlying this body plan are completely unknown, but are critical in understanding how echinoderm pentamery evolved from bilateral ancestors. These mechanisms are difficult to study in indirect-developing species; in this study, we use the direct-developing sea(More)
AIM To explore gender differences and similarities on personal, employment and work-life factors and predictors of job satisfaction among registered nurses in rural and remote Canada. BACKGROUND Research suggests that men and women are attracted to nursing for different reasons, with job security, range of employment opportunities and wages being(More)
The transcription factors Gsc and Msx are expressed in the oral ectoderm of the indirect-developing sea urchin Heliocidaris tuberculata. Their patterns of expression are highly modified in the direct developer Heliocidaris erythrogramma, which lacks an oral ectoderm. We here test the hypothesis that they are large effect genes responsible for the loss of(More)
During the evolution of direct development in the sea urchin Heliocidaris erythrogramma major modifications occurred, which allowed the precocious formation of adult-specific structures and led to a novel larval body that surrounds these structures. The HeET-1 gene was isolated in a differential screen for transcripts enriched in the early embryos of H.(More)
The sea urchin SpEGF 1 gene belongs to a growing family of developmentally important genes which encode proteins that contain repeated epidermal growth factor-like motifs. To characterize the embryonic expression of the protein products of this gene from Strongylocentrotus purpuratus, we generated polyclonal antisera from SpEGF I fusion proteins. These(More)
Research on nursing practice issues in rural and remote areas of Canada is very limited. This report describes the method and initial results of a comprehensive survey of registered nurses (RNs) practising outside the commuting zones of large urban centres, designed to determine: who practises nursing in rural and remote Canada; the nature and scope of(More)
We describe the Hox cluster in the radially symmetric sea urchin and compare our findings to what is known from clusters in bilaterally symmetric animals. Several Hox genes from the direct-developing sea urchin Heliocidaris erythrogramma are described. CHEF gel analysis shows that the Hox genes are clustered on a < or = 300 kilobase (kb) fragment of DNA,(More)
A sea urchin DNA clone complementary to an embryonic messenger RNA whose protein product bears striking homology to the epidermal growth factor family of proteins has been identified and characterized. The structure of the protein is similar to that of previously identified regulatory genes in Drosophila and Caenorhabditis. RNA gel blot hybridization showed(More)