RT-PCR profiling of L. vannamei prepro-NPFs in nervous system, midgut and skeletal muscle. Using a gene-specific primer that amplifies products from both Litva-PP-NPF I and II, RT-PCR tissue profiling was conducted to assess the distributions of the two transcripts. A strong band of the predicted Litva-PP-NPF I product (374 bp in length) was consistently detected in eyestalk ganglia (EG; lane 1), brain (Br; lane 2), thoracic ganglia (TG; lane 3) and abdominal ganglia (AG; lane 4). Weaker bands corresponding to the predicted Litva-PP-NPF II product (485 bp in length) were consistently detected in these tissues as well. A weak band corresponding to the Litva-PP-NPF I product was detected in some, but not all midgut samples (Mg; lane 5); no detection of the Litva-PP-NPF II product was seen in this tissue. Neither Litva-PP-NPF I nor Litva-PP-NPF II was detected in samples of skeletal muscle (SM; lane 6). A base pair ladder (L) is shown in lane 7.