Hagfish vwf is expressed as a single gene product. (A) PCR primer pairs A1/S1 and A2/S2 (supplemental Table 1) were used to generate DNA products from the A2 domain or from a region of the A2 domain to the C2-C3 spacer from hagfish vwf cDNA prepared by reverse transcription from hagfish heart, liver, gill, and skin RNA. Only the expected 189-bp and 333-bp PCR products were observed on agarose gel analysis. (‐‐) Control reactions without template cDNA. (B) Northern blot hybridization of hagfish RNA from heart and gill with probes that spanned either the A1-A2 region or the 3′ untranslated region (UTR) from the hagfish vwf gene (supplemental Table 1). A single 7.5-kb transcript is observed in both heart and gill.