Figure 1: (a) 32P-labeled probes hybridized to sex-differentiating genes on filters representing the BAC library for painted turtle (Chrysemys picta). Two-dot signals permit the gridding of multiple 384-well plates into the same space on the filters. The two-dot pattern permits the gridding of up to 72 384-well plates on one nylon filter. Arrows indicate successful hybridization of one of several probes applied concurrently to filters. (b) Clones identified as putative positives from hybridization with a probe for Dmrt1 regridded in duplicate onto a separate filter to be hybridized with a single probe as opposed to the multiprobe approach taken to initially identify positives. The secondary hybridization permits the identification of the probe that hybridizes to each positive. Arrows indicate three hybridizations that occurred on each of two identical arrays representing only positives collected from the initial large-scale hybridization. These arrays are printed side by side on the filter. Other hybridizations that were successful in only one array were rescreened to insure replicability.