Figure 1.

The SpTransformer (SpTrf) genes are expressed in response to immune challenge. Two arrayed cDNA libraries constructed from coelomocytes: (A) collected from six sea urchins after immune challenge by injection of marine bacteria or (B) collected from six sea urchins that were not challenged. Individual colonies harboring cDNAs were arrayed into 91,920 separate wells in 240 plates of 384 wells/plate. cDNA inserts for each colony were amplified, spotted onto a nylon filter [for details, see Ref. (10)], and both libraries were screened with a ³²P-RNA probe constructed from a set of SpTrf cDNA clones (9). The activated library has ~5,925 SpTrf-positive spots or 6.45% of the library, whereas the non-activated coelomocyte library has 79 SpTrf-positive spots or 0.086% of the library. Positive clones are indicated by two spots within a 4 × 4 set of amplified insert cDNA from each clone in the library. (C) Coelomocytes collected over time from three immunoquiescent sea urchins and analyzed by RT-PCR show changes in the SpTrf amplicon sizes before vs. after one or two injections of lipopolysaccharide (arrows). The major element pattern identified after cDNA insert sequencing is E2 has an amplicon size of about 935 nt, which is similar to the single band observed at 24–48 h post challenge. Panel (C) is reprinted from Ref. (11).