Telerehabilitation for neck pain.

Recently, we completed whole-genome sequencing and assembly in []. Because octopuses are thought to be the most behaviorally advanced invertebrates, this resource enables testing of molecular homology for complex behaviors, despite anatomical differences in brain organization across evolutionarily distant lineages []. In this context, it is interesting to note that in vertebrates (humans and rodents), the phenethylamine (+/−)-3,4-methylendioxymethamphetamine (MDMA) is known for its powerful prosocial properties [–]. Furthermore, the sixth trans-membrane domain (TM6) of the serotonin transporter (SERT), encoded by the gene [], has been identified as the principle binding site of MDMA [–]. To determine whether this binding site is conserved in , we performed a molecular phylogenetic analysis of the solute carrier (SLC) 6A subfamily of neurotransmitter transporter proteins [] across selected diverse taxa ( and ). Blasting a reference gene set against 21 proteomes resulted in a final set of 503 sequences. These sequences were used to generate a maximum-likelihood phylogenetic tree (RAxML’s “best tree”) for SLC6A across all 21 species (; , , and ), along with 156 bootstrap trees and a bootstrap ‘‘consensus tree’’ (). The ‘‘best tree’’ included the full set of human SLC6A genes and no additional human genes from other SLC families (; and ; ). Expected SLC6A4 family members were found for the fruit fly (), the worm (), and all vertebrate species tested, although the ‘‘best tree’’ () and the ‘‘consensus tree’’ () differed slightly for the worm. Surprisingly, two copies of SLC6A4 were found in mollusks, including One copy in octopuses, named here (protein Ocbimv22009795m.p; gene model Ocbimv22008529m.g) was part of a clade that contained only mollusks. The second copy, named here (protein Ocbimv22009795m.p; gene model Ocbimv22009795m.g), was in a group that included diverse species, like the fly and worm, but no mammals, vertebrates, or other deuterostomes. It is un-clear whether this duplication is a molluscan innovation or has more ancient origins in the Lophotrochozoa. Two and three copies of SLC6A4 were present in the zebrafish () and zebra finch (), respectively, but only a single copy was present in mammals and in basal-branching deuterostomes. These patterns may reflect differential loss of SLC6A4 after two rounds of vertebrate genome duplication [], with a single copy in the ancestral vertebrate, and losses of three copies in mammals, two copies in fish, and one copy in birds (). In contrast to the octopus, the honeybee (), leaf cutter ant (), spider (), and anemone () all lacked SLC6A4 orthologs. To understand these losses, we next examined all monoamine transporters, including human SLC6A2 (DAT), SLC6A3 (NET), and SLC6A4 (SERT), along with their outgroup, a branch that includes the fruit fly inebriated () gene ( and ). Anemones had multiple paralogs within the clade. Zebrafish and more basal-branching deuterostomes were also present, but other vertebrates, including humans, were absent. In contrast, the anemone was absent in SLC64A and throughout the monoamine transporter clade. Thus, monoamine transporters may represent an ancient innovation that arose early in bilaterian evolution, with various ancient and more recent duplications in different lineages. Representing ecdysozoans, the honeybee, leaf cutter ant, fruit fly, and worm all had one or more monoamine transporter proteins outside the SLC6A4 family, whereas only the fruit fly and worm had proteins within the family, suggesting that SLC6A4 has been lost in hymenopteran insects (ants, bees, wasps, and sawflies). Interestingly, although many of the invertebrates lacking SLC64A orthologs are eusocial, this adaptation is not ubiquitous across all eusocial species, since the SLC6A4 gene is conserved in the naked mole rat (), which is a eusocial vertebrate. Taken together, these studies underscore the complexity of monoamine transporter evolution in animals and identify clear orthologs of human SLC6A4 in octopuses. The binding pocket of SLC6A4 is formed by a subset of 12 transmembrane domains, including TM6 []. Previous studies have revealed an especially important role for the region of TM6 that spans amino acids 333 to 336 (indicated in green in ), as it provides an overlapping binding pocket for MDMA and serotonin []. Furthermore, residue Ser336 has been implicated in the MDMA-induced conformational change not observed with serotonin []. Significantly, for both octopus orthologs within this region, there is 100% percent identity when aligned to human SLC6A4 (; ). More generally, many of the domains forming the binding pocket are highly conserved in comparison to other domains and to the full-length protein (). For instance, TM6 in Slc6a4-(1) has 95.7% identity to human SLC6A4, compared to 53.4% for the whole protein, and TM8 in Slc6a4-(2) has 91.0% identity to human SLC6A4, compared to 39.0% for the whole protein (). This work further demonstrat