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Development 2012 Oct 01;13920:3786-94. doi: 10.1242/dev.082230.
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Autonomy in specification of primordial germ cells and their passive translocation in the sea urchin.

Yajima M , Wessel GM .

The process of germ line determination involves many conserved genes, yet is highly variable. Echinoderms are positioned at the base of Deuterostomia and are crucial to understanding these evolutionary transitions, yet the mechanism of germ line specification is not known in any member of the phyla. Here we demonstrate that small micromeres (SMics), which are formed at the fifth cell division of the sea urchin embryo, illustrate many typical features of primordial germ cell (PGC) specification. SMics autonomously express germ line genes in isolated culture, including selective Vasa protein accumulation and transcriptional activation of nanos; their descendants are passively displaced towards the animal pole by secondary mesenchyme cells and the elongating archenteron during gastrulation; Cadherin (G form) has an important role in their development and clustering phenotype; and a left/right integration into the future adult anlagen appears to be controlled by a late developmental mechanism. These results suggest that sea urchin SMics share many more characteristics typical of PGCs than previously thought, and imply a more widely conserved system of germ line development among metazoans.

PubMed ID: 22991443
PMC ID: PMC3445309
Article link: Development
Grant support: [+]

Genes referenced: ddx4 LOC100887844 LOC100891456 LOC115919910 LOC594236 pole
Morpholinos: pqlc2l MO1

References [+] :
Aihara, Left-right positioning of the adult rudiment in sea urchin larvae is directed by the right side. 2001, Pubmed, Echinobase