Simple protocol for extracting nuclear DNA from single embryos of a marine snail.

1050 BioTechniques Vol. 26, No. 6 (1999) DNA in solution were used instead of 10.75 μL of ddH2O and 8.5 μL of DNA in solution. The re-amplified eluted band was electrophoresed, gel-purified and cloned into a pGEM-T vector (Promega, Madison, WI, USA). We then identified clones containing recombinant plasmids, isolated plasmid DNA and used the insert of an individual clone as a hybridization probe in northern blot analysis. A single hybridizing mRNA of approximately 520 bases was identified in the lanes corresponding to the CM and, to a lesser extent, the 90-day-old WT hamster ventricles (Figure 1C). By using the re-amplified band of interest as a hybridization probe against northern blots, we were able to isolate, clone and identify a differentially expressed cDNA despite the fact that numerous cDNA species were present in the original band obtained. The ability to isolate and clone DNA that has hybridized to specific mRNA species should increase the speed of the secondary screening following DD and should eliminate the possibility that positive bands are not discarded simply because the specific clone is overlooked in the secondary screening analysis.