| Functional |
"SLC4A9 encodes an electroneutral ion exchange protein (51), which is expressed in the submandibular salivary gland. SLC4A9 is restricted to the basolateral membrane of acinar cells, where it participates in saliva secretion (Fig. 4B) (52)." |
10.1126/sciadv.aaw6671 |
| Timing of Loss |
"Several shared inactivating mutations indicate that SLC4A9 (solute carrier family 4 member 9) was lost in the cetacean stem lineage. Visualization as in Fig. 1A." |
10.1126/sciadv.aaw6671 |
| Phenotypic |
"SLC4A9 knockout mice displayed a 35% reduction in saliva secreted from the submandibu
lar gland (52). This suggests that loss of SLC4A9 in cetaceans could contribute to a reduction of saliva secretion, which is in agreement with morphological observations that salivary glands are absent or
atrophied in cetaceans (53)." |
10.1126/sciadv.aaw6671 |
| Phenotypic |
"For species living in a hyperosmotic environment, where they incidentally ingest seawater with their prey, salt reabsorption by the kidney is probably less important (or even harmful) relative to efficient salt excretion. Thus, the loss of the salt reabsorbing factor SLC4A9 may contribute to the high urinary concentrations of sodium and chloride in cetaceans as compared to cows (57)." |
10.1126/sciadv.aaw6671 |