22,30,44) Otx is not activated at the 16-cell stage, because an additional activator is required for its expression: the secreted signaling molecule Fgf9/ 16/20, the sole ortholog
of vertebrate FGF9, FGF16 and FGF20, which is expressed in the vegetal hemisphere from the 16-cell stage.
For example, although the estrogen receptor (ER) is well conserved across vertebrate species (Baker 2011), a functional ortholog
has not been found in invertebrate species (Baker et al.
Other studies have suggested that the zebrafish Aqp0b ortholog
of mammalian AQP0, which also functions as a cellular adhesion molecule (Costello et al.
2010) Human [beta]-defensin 2 and 3 and their mouse orthologs
induce chemotaxis through interaction with CCR2.
Data are transferred between organisms by using the InParanoid Eukaryotic Ortholog
Groups' database (InParanoid 2009; O'Brien et al.
japonica were assessed using a publicly available ortholog
sequence from the latter (Genbank accession no.
An excellent chapter on the Fet3 protein, which is the yeast ortholog
of ceruloplasmin is, however, included.
Interestingly, rapid transport of an AQP8 ortholog
into the mitochondria of activated spermatozoa was also noted recently in the Atlantic salmon Salmo salar (Chauvigne et al.
The human ortholog
of the yeast MTQ2 is N-6 adenine-specific DNA methyltransferase 1 (N6AMT1), encoding a putative methyltransferase.
These findings suggest that the homolog or ortholog
of these fish aqps might have given rise to tetrapod aqp2, aqp5, and aqp6 via gene duplication (Konno et al.