Background: Oocyte maturation is an important prerequisite for the production of progeny. Although several germ-line mutations have been reported, the precise mechanism by which the last step of oocyte maturation is controlled remains unclear. In Caenorhabditis elegans, CCCH-type zinc-finger proteins have been shown to be involved in germ cell formation, although their involvement in oocyte maturation has not been fully investigated.

Results: Using a multiple RNAi technique, we have identified three novel redundant CCCH-type zinc-finger genes, named by us moe-1, -2 (oma-1, -2) and moe-3, as a group related by functions and nucleotide sequence. Although a single RNAi of each moe gene was not effective, double or triple RNAi induced defects in oocyte maturation. We found that each moe transcript was expressed from the distal to proximal region of the gonad, while their corresponding proteins are accumulated exclusively in proximal oocytes, with a close association to germ granules. Although MOE-2 protein is rapidly removed from germ granules after fertilization, we found that MOE-2 associates with the centrosome-peripheral structure in dividing blastomeres.

Conclusions: Our results suggest that moe gene products are unique multifunctional proteins in terms of their redundancy and characteristic behaviour during the course of oocyte maturation. These gene products participate in processes in the final step of the meiotic cell cycle control, a novel function for CCCH-type zinc-finger family proteins thus far discovered.