Embryonic diapause is an arrest in development at the blastocyst stage. Diapause occurs in about 30 marsupial species among which the best studied macropodid marsupial is the tammar wallaby Macropus eugenii.In tammars, diapause is normally maintained for at least 11 months.  During the first half of the year (Jan-June), the sucking stimulus of the pouch young maintains diapause while in the second half of the year diapause is mediated by photoperiod. The tammar blastocyst lies free and unattached in the uterus, so reactivation is caused by signals from the uterine secretions. There are marked changes in some uterine proteins during diapause and reactivation, but the exact proteins which differentiate these two phases still remains unclear.

In order to understand the molecular mechanisms involved in entry, maintenance and reactivation from diapause, endometrial tissue lysate and exudates from endometrium at day 9 of pregnancy after diapause and from a quiescent uterus carrying a diapausing blastocyst were analysed. The proteins were extracted using a lysis buffer, fractionated by 1D SDS PAGE and fractions excised and digested with trypsin. The peptide mixtures from each fraction were analysed on a cHiPLC nanoflex system coupled to a tripleTOF mass spectrometer. The LC-MS/MS datasets were analysed using a tammar protein dataset on Mascot, a search engine for protein identification. The lysates contained of numerous proteins from muscle, tissue, cells and several enzymes and intermediates involved in biochemical pathways. The exudates were dominated by major serum proteins apart from the muscle proteins and proteins involved in biochemical pathways.These data provide detailed information on the proteins that are differentially expressed during diapause and after reactivation from diapause.