Variability in laser-induced venous occlusion, an fga exon 6 polymorphism and fibrinogen quantity and quality in zebrafish strains. (A) The TTO after laser injury of the PCV in 3-dpf TU (n = 20), AB (n = 18), or TU × AB (n = 19) larvae is represented. The TU strain TTO is significantly shorter than that of AB, but not significantly different (ns) from that measured in TU × AB larvae (Mann-Whitney U tests). Each circle represents an individual larva. (B) Small stretches of Sanger sequencing chromatograms of part of fga exon 6 PCR-amplified from TU, AB, and TU × AB larvae. The sequencing is in the reverse direction to the fga open reading frame. A single-nucleotide deletion can be seen in the AB strain plot, compared with TU, and then heterozygosity at this position in the TU × AB larvae. (C) The consequences of this single-nucleotide change for AαE translation are highlighted. In the top alignment, the sequences begin with the proline 474 codon; the nucleotide deleted in the AB strain is underlined in the TU DNA sequence. Three missense residues are encoded after the deletion in the AB strain (LRR, in gray) before a TAG (UAG in mRNA) terminator. The bottom alignment shows the AαE sequence from the start of the fga exon 6-encoded residues, in TU, AB, and human (Hs) AαE. In AB, translation is predicted to terminate after 27 codons instead of 236 in TU or human AαE. Asterisks (*) show identical aligned residues in TU and human AαE. (D) An immunoblot for detection of zebrafish fibrinogen AαE and β-actin in whole-larvae lysates from 3-dpf TU, AB, and TU × AB larvae in reduced conditions. (E) For further interstrain comparison, additional blots in which 3 independent pools of AB and TU larvae were used are shown.