Sequence analysis, gene copy number and pituitary expression of grass carp activin βA and βB.

(A) Phylogenetic analysis of carp activin βA and βB cDNA sequences with corresponding sequences reported in other species using neighbour-joining method with MEGA 6.0. The numbers presented with individual nodes of the guide tree are the percentage of bootstrap values based on a 1000 bootstraps. (B) 3D protein modelling of grass carp activin βA and βB using SWISS-MODEL and DeepView with the crystal structures of human activin βA and βB as the template, respectively. The regions in red represent the α2 and α3 helical domains while the two pairs of antiparallel β strands forming the main core of activin β subunit are marked in blue. (C) Gene copy number for activin βA and βB deduced by genomic Southern. Southern blot was conducted with DIG-labelled probes for activin βA and βB, respectively, in grass carp genomic DNA with prior digestion of the restriction enzymes as indicated. (D) Characterization of activin βA and βB transcripts expressed in the carp pituitary. Total RNA was isolated from the carp pituitary, resolved in 1% agarose gel and subjected to Northern blot with DIG-labelled probes for activin βA and βB. Parallel blotting for β actin mRNA was used as the internal control. (MK: Size markers for RNA transcripts).