| Mutation Description |
"MMP12 has a stop codon (asterisk) that is shared between all four cetaceans. Also, the deletion of exons 6-8 (asterisk) has the same breakpoints in the minke and sperm whale. This shows that MMP12 loss already happened in the cetacean ancestor before the split of the toothed and baleen whale lineage." |
10.1038/s41467-018-03667-1 |
| Methodology & Validation |
"For a gene to be classified as lost, we require that a lineage, which descends from an ancestor with an intact gene, exhibits several gene-inactivating mutations that most likely result in a non-functional protein. As gene-inactivating mutations, we consider frameshifting insertions and deletions, inframe stop codon mutations, and splice site-disrupting mutations. In addition, we consider the loss of exons or even entire genes, which could occur due to either large deletions in the genome or the accumulation of numerous mutations that destroy any sequence similarity. For all previously unknown gene losses presented here, we further confirmed the loss by validating the gene-inactivating mutations with unassembled sequencing reads from the respective species." |
10.1038/s41467-018-03667-1 |
| Timing of Loss |
"Supporting this, MMP12 loss predates the split of the fully aquatic toothed and baleen whale lineages and happened early in the fully aquatic sirenia (manatee) lineage (Supplementary Table 5)." |
10.1038/s41467-018-03667-1 |
| Phenotypic |
"(…) the loss of MMP12 in cetaceans and manatees could relate to MMP12’s potent elastase activity, which degrades elastin in the extracellular matrix and is the main factor regulating elastin levels. (…) Thus,
the specific loss of the elastin degrading MMP12 suggests a mechanism that could contribute to the extensive elastic lung tissue necessary for explosive exhalation." |
10.1038/s41467-018-03667-1 |