Microinjection of plasmids into meiotically incompetent mouse oocytes.

RNA interference (RNAi) is a suitable method for sequence-specific post-transcriptional gene silencing in a number of model systems. The following protocol describes delivery of a mammalian double-stranded RNA (dsRNA) expression vector into meiotically incompetent mouse oocytes by microinjection. During mouse oocyte growth, there is a progressive decline in transcriptional activity, such that the fully-grown oocyte is transcriptionally quiescent. For this reason, the microinjection of plasmids should be performed in growing oocytes, obtained from 12- to 13-d-old females. Microinjected oocytes can be cultured for up to 2 d. The efficiency of knockdown by RNAi can be assayed by quantitative reverse transcriptase (RT)-PCR (qPCR).