Primary amino acid sequence similarity for 86 proteins implicated in BBB
development (see figure 4) was determined
for species representing classes that appear at different times throughout
evolutionary history: (Mammalia: Homo sapiens, Pan troglodytes, Mus
musculus; Actinopterygii (ray-finned fish): Danio
rerio; Chondrichthyes (cartilaginous fish): Callorhinchus
milii; Leptocardii (earliest vertebrates): Branchiostoma
belcheri; Branchiopoda (crustaceans): Daphnia
magna; Insecta: Musca domestica; Hyperoartia
(invertebrate chordate): Lethenteron camtschaticum;
Cephalopoda: Eteroctopus dofleini). Comparisons to the human
protein (100%) were made by an amino acid sequence query using the Basic Local
Alignment Search Tool for proteins (BLASTp) of the National Center for
Biotechnology Information (NCBI) protein database using SeqAPASS v2.0 software
(https://seqapass.epa.gov/seqapass) (LaLone et al., 2016), which facilitates consistent
comparisons of amino acid sequence similarity across multiple species. For
proteins with multiple isoforms, SeqAPASS best practices were used to select the
most representative NCBI protein accession number for the BLAST; and full
sequence lengths (rather than functional domains) were used. A beta testing
version of ToxPi software v2.0 provided by David Reif (NCSU) was used to produce
the sequence similarity ToxPis using the ‘single’ clustering
algorithm (Reif et al., 2010). For each
protein, the % similarity to the human protein (100%) is represented by the
length of pie slice (i.e., shorter pie slices represent lower similarity; or
absence of a slice indicates no sequence similarity). Slices are arranged from
highest to lowest % similarity in the mouse compared to humans (i.e., red slices
have the highest similarity and light purple slices represent the lowest
similarity). The type of BBB (glial or endothelial) is indicated on the
dendrogram at the node representing a common ancestor with the same type of BBB.
The symbols listed in the ‘protein’ key correspond to standard
NCBI gene names. NCBI protein database accessed between 6/27/17 and 7/27/17.