The mitochondrial genome of the hexactinellid sponge Aphrocallistes vastus: Evidence for programmed translational frameshifting

Table 2 Exceptional mtDNA codon usage

For each sponge species with a published mtDNA, the number of occurrences in protein coding sequence is given of codons with exceptional usage (A.v., Aphrocallistes vastus; I.p., Iphiteon panicea; S.n., Sympagella nux; A.q. Amphimedon queenslandica; A.c., Axinella corrugata; G.n., Geodia neptuni; T.a., Tethya actinia; O.c., Oscarella carmela). The hexactinellid sponges strongly favor Ile(AUA) despite coding for a tRNA with (gau) specificity. AGR codons (in bold) are reassigned from arginine to serine in the glass sponges. The hexactinellids rarely if ever employ the Trp(UGG) codon for translation, but rather seem to use it as a signal for programmed frameshifting.

ISSN: 1471-2164