Analysis of All V Arms

In the above network, red nodes correspond to tRNALeu V arm sequences and blue nodes correspond to tRNASer V arm sequences. Connected components containing fewer than four nodes have been removed for visual clarity. The main point to note is that there is only one edge in this network linking a sequence in the tRNALeu V arm set to a sequence in the tRNASer V arm set. The two sequences are UGGGCGUCAGGCCCGC (tRNALeu) and UGGGCGUCAGCCCGC (tRNASer), which are linked by an indel mutation. This means that if there are other relations between the tRNALeu and tRNASer sequences as we hypothesize, then these relations likely involve at least three nucleotides since our analysis checks for the most common one- and two-nucleotide transformations.

Future analysis may require looking more broadly for changes in the structure of the V arms between different species rather than focusing on the specific nucleotide-level changes for each sequence. For example, one structural relation between two sequences that we do not consider in our analysis is a change in the V arm stem length. Most tRNALeu sequences have a stem length of 3, while most tRNASer sequences have a stem length of 4 or 5. By comparing sequences with similar structures aside from a difference in stem length, it may be possible to observe patterns in these sequences that are not apparent when considering only one or two nucleotides at a time.