Cloning and characterization of a new gene from the PAT protein family, in a marsupial, the stripe-faced dunnart (Sminthopsis macroura).

Recent studies of PAT proteins in Drosophila and Xenopus have revealed significant roles for this family of proteins in the polarized transport of lipid droplets and maternal determinants during early embryogenesis. In mammals, PAT proteins are known to function mainly in lipid metabolism, yet research has yet to establish a role for PAT proteins in mammalian embryogenesis. Oocytes and early cleavage stages in Sminthopsis macroura show obvious polarized cytoplasmic distribution of organelles, somewhat similar to Drosophila and Xenopus, suggesting that a PAT protein may also be involved in S. macroura embryonic development. In the present study, we identified a new marsupial gene for PAT family proteins, DPAT, from S. macroura. Expression analyses by RT-PCR and whole mount fluorescent in situ hybridization revealed that DPAT expression was specific to oocytes and cleavage stage conceptuses. Analysis of the localization of lipid droplets during S. macroura early embryonic development found a polarized distribution of lipid droplets at the two- and four-cell stage, and an asymmetric enrichment in blastomeres on one side of conceptuses from two- to eight-cell stage. Lipid droplets largely segregate to pluriblast cells at the 16-cell stage, suggesting a role in pluriblast lineage allocation.