Detection of circular and linear transcripts of Sry in pre-implantation mouse embryos: differences in requirement for reverse transcriptase.

Sry is the testes determining factor gene located on the Y chromosome. Expression of Sry had previously been found to occur during a short time frame of 10.5 to 12.5 days post coitum in the developing genital ridge. A recent study of the Sry transcript from adult testes found that the most abundant transcript is circular in nature. We have performed reverse transcription polymerase chain reactions with RNA from mouse preimplantation embryos ranging from the 2 cell stage to the blastocyst stage and report the detection of both circular and linear forms of Sry in the preimplantation embryo. In addition, we also demonstrate that the well described reverse transcriptase activity of Taq polymerase leads to a major difference in the mode of detection of the two forms.