Many maternally provided transcripts play crucial roles in early development and often require tight translational regulation. During C. elegans embryogenesis, the maternal transcript nanos-2(nos-2) is translationally repressed until the germline founder cell,called P4, is born. In their dissection of this process (see ), Kuppuswamy Subramaniam and co-workers have discovered that four additional proteins(OMA-1, OMA-2, MEX-3 and SPN-4) are involved in this repression of nos-2. These proteins bind to the 3′ UTR of nos-2 and repress it at different developmental stages: OMA-1 and OMA-2 in oocytes, and MEX-3 and SPN-4 in the embryo. What eventually releases nos-2repression in P4, the authors propose, is the competition between SPN-4 and POS-1 (a protein required for nos-2 translation) to bind to nos-2. Thus, POS-1 works, not by activating translation, but by de-repressing it; as such, the authors believe that the relative concentrations of POS-1 and SPN-4 have a crucial role in initiating germ cell-specific developmental programmes.
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