Protein databases for compacted eight-cell and blastocyst-stage mouse embryos

High‐resolution two‐dimensional sodium dodecyl sulfate‐polyacrylamide (2D‐SDS) gel electrophoresis combined with computerized analysis of gel images was used to construct and analyze protein databases for two stages of preimplantation mouse embryogenesis, the compacted eight‐cell stage and the fully expanded blastocyst stage. These stages were chosen for their ease in identification of multiple synchronous embryos. Synchronous cohorts of 30–50 embryos were labelled with L‐[35S]methionine for 2 hr. The embryos were then lysed in 30 μl hot SDS sample buffer, and the lysates were stored at −80°C until the gels were run. Five replicates were run for eight‐cell embryos, and four for blastocyst‐stage embryos. The samples were processed for 2D gel electrophoresis and fluorography; multiple exposures were made. Gel images were analyzed using the PDQUEST system, and databases were constructed. Analysis of the databases for both developmental stages showed high reproducibility of protein spots in multiple gel images. Of 1,674 total spots in eight‐cell embryo standards, >79% of spots had a percentage error (S.E.M./average) 45% had a percentage error