Vertebrate Development Maternal to Zygotic Control (Advances in Experimental Medicine and Biology)

388

Table 8.1

(continued)

Germ name

Protein

Expression/Phenotype

Function

Reference

Ziwi/Zili

RNA binding proteins

Proteins specifically expressed in germ cells. Loss of Ziwi function results in a progressive loss of germ cells due to apoptosis during larval development

Ziwi proteins associate with a class of germ-cell-

specific small RNA molecules named Piwi-

Interacting RNAs (piRNAs). Have a role in germ cell maintenance and transposon silencing

Houwing et

al.

(^2007

)

Buc (Buckyball)

Novel protein (unrelated to any known family protein)

Buc protein localizes within the Balbiani body. Mutants present defects in germ plasm localization and polarity. Overexpression generates ectopic germ cells in the zebrafish embryo

Germ plasm defect in bucky ball mutants precedes the loss of polarity, indicating that Buc primarily controls Balbiani body formation

Bontems et

al.

(^2009

) Heim

et

al. (

2014

)

Tdrd7 (Tudor domain containing protein-7)

RNA binding proteins

Tdrd7 transcripts are localized in germ plasm and are expressed in PGCs for at least the first days of development. Despite normal PGC specification and migration observed in

Tdrd7

morphants,

germ cell granule structure integrity is abnormal

Tdrd7 has a critical role for structural integrity of granules in PGCs

Strasser et

al.

(^2008

)

Mgn (Magellan microtubule actin crosslinking factor 1 [macf1] gene

Spectraplakin family of cytoskeletal linker proteins

Zebrafish magellan mutant exhibits a novel enlarged Balbiani body phenotype and a disruption of oocyte polarity

In mgn mutants, the oocyte nucleus is mislocalized; and the Balbiani body, localized mRNAs, and organelles are absent from the periphery of the oocyte, consistent with a function for macf1

in nuclear anchoring and cortical

localization

Gupta et

al.

(^2010

)

Pum 1/2 (Pumilio2)

Puf family of RNA-binding proteins

pumilio-2

are distributed in all blastomeres from the 1-cell stage to

Gastrulation. Then accumulate in head and tail during early segmentation. Pumilio-2 protein is strongly expressed in the ovary, testis and brain

Translational repression of target mRNA.

Pumilio

proteins regulate the translation of specific proteins required for germ cell development and morphogenesis

Wang et

al.

(^2009

) and

Kotani et

al.

(^2013

)

Puf-A

Puf family of RNA-binding proteins

Knockdown of

puf-A

resulted in microphthalmia, a small head, and

abnormal PGC migration

puf-A

plays an important role not only in eye

development, but also in PGC migration and the specification of germ cell lineage

Kuo et

al.

(^2009

)

Brul (Bruno-like)

Elav-type RNA-binding protein that belongs to the Bruno-like family

mRNA protein of brul are localized to the germ plasm at the ends of the cleavage furrows

Brul genes may have a conserved function in axis specification (Dm analogy) and germ cells maintenance

Hashimoto et

al. (

2006

)

T. Aguero et al.