387Table 8.1Genes related to germ cell development in zebrafishGerm nameProteinExpression/PhenotypeFunctionReferenceNanos1RNA binding zinc-finger proteinsNanos-1 mRNA is expressed in the germ plasm and in the germ cells until 5dpf. PGCs with lower levels of Nanos-1 havemigration defects and eventually dieActs as a translational repressor that regulates translation of specific mRNAs by forming a complex with Pumilio that associates with the 3 ′
-UTR of mRNA targetsKoprunner etal.(^2001)DazlRNA binding proteinsDepletion of maternal Dazl mRNA in early embryos results in significant depletion of PGCs in Zf larva. DAZL overexpression strongly induces somatic protein expressionDAZL activates the translation efficiency of the target mRNAs through direct binding to cis-elements in their 3′ UTRs. Interacts withpoly(A)-binding proteins, which are critical for the initiation of translation. Protect mRNAs against miRNA repression in germ cellsTakeda etal.(^2009) and
Hashimoto et
al. (2004)Dead end 1 (dnd1)RNA binding proteinsKnockdown of dnd1 blocks confinement of PGCs to the deep blastoderm and results in failure of PGCs motile behavior and to actively migrate thereafter. PGCs subsequently dieProtect mRNAs against miRNA repression in germ cellsWeidinger etal.(^2003)VasaA DEAD-box RNA helicaseVasa RNA expressed in germ plasm, PGCs and germ cells during gametogenesis. Protein is initially uniformly distributed but becomes restricted to the PGCs during gastrulation. Mutations disrupting vasa cause sexually dimorphic infertility, with impaired development of the ovary testisCrucial role during germ-line specification, migration, survival, and maintenance. Involved in female meiosis, differentiation, and maintenance of germ-line stem cellsHartung et
al. (2014)Cxcr4bSeven transmembrane G-protein coupled receptorcxcr4b RNA is maternally provided and during gastrulation becomes expressed in specific tissues including the PGCs, which migrate towards domains of sdf-1a RNA expressionCxcr4b receptor for the chemokine Sdf1a. Critical role in PGC migration, required specifically for their chemotaxisKnaut etal.(^2003)Sdf-1a (stromal cell-derived factor-1)ChemokineMutant are able to activate the migratory program, but fail to undergo directed migration towards their target tissue, resulting in randomly dispersed germ cellsSdf1a guides migrating PGCs towards their intermediate and final targetsKnaut etal.(^2003) and
Mizoguchi et
al. (2008)Staufen1/2RNA binding proteinsKnock down embryos affect expression of the PGC markervasa.Zf Stau proteins have evolutionarily conserved functions in germ cells and in neuronsStau1 and Stau2 proteins are involved in survival and maintenance of germ cells. PGC migration is aberrant, and the mis-migrating PGCs do not survive in Stau-compromised embryosRamasamy et
al. (2006)(continued)8 Mechanisms of Vertebrate Germ Cell Determination