Parallel Evolution of Auditory Genes for Echolocation in Bats and Toothed Whales

The ability of bats and toothed whales to echolocate is a remarkable case of convergent evolution. Previous genetic studies have documented parallel evolution of nucleotide sequences in Prestin and KCNQ4, both of which are associated with voltage motility during the cochlear amplification of signals. Echolocation involves complex mechanisms. The most important factors include cochlear amplification, nerve transmission, and signal re-coding. Herein, we screen three genes that play different roles in this auditory system. Cadherin 23 (Cdh23) and its ligand, protocadherin 15 (Pcdh15), are essential for bundling motility in the sensory hair. Otoferlin (Otof) responds to nerve signal transmission in the auditory inner hair cell. Signals of parallel evolution occur in all three genes in the three groups of echolocators—two groups of bats (Yangochiroptera and Rhinolophoidea) plus the dolphin. Significant signals of positive selection also occur in Cdh23 in the Rhinolophoidea and dolphin, and Pcdh15 in Yangochiroptera. In addition, adult echolocating bats have higher levels of Otof expression in the auditory cortex than do their embryos and non-echolocation bats. Cdh23 and Pcdh15 encode the upper and lower parts of tip-links, and both genes show signals of convergent evolution and positive selection in echolocators, implying that they may co-evolve to optimize cochlear amplification. Convergent evolution and expression patterns of Otof suggest the potential role of nerve and brain in echolocation. Our synthesis of gene sequence and gene expression analyses reveals that positive selection, parallel evolution, and perhaps co-evolution and gene expression affect multiple hearing genes that play different roles in audition, including voltage and bundle motility in cochlear amplification, nerve transmission, and brain function

Recurrent desmoids determine outcome in patients with Gardner syndrome: a cohort study of three generations of an APC mutation-positive family across 30 years

PURPOSE: Screening of Gardner syndrome (GS) patients is tailored towards prevention of colorectal cancer (CRC). However, many patients suffer from desmoid tumors, which are challenging to treat due to invasive growth and local recurrence. The aims of our study were to determine the effectiveness of screening in GS and analyze outcome of desmoid tumors by treatment modality. METHODS: This was a cohort study of a family of 105 descendants with GS. All family members who agreed were screened by endoscopy, and colorectal resection was performed upon pending malignancy. Resectable desmoids were excised, whereas large tumors were treated by a combination of brachytherapy (BT) and radiotherapy (RT). Main outcome measures were the incidence of CRC and overall and disease-specific mortality (ClinicalTrial.gov ID NCT01286662). RESULTS: Thirty-seven of 105 family members have GS. Preventive colorectal resections were performed in 16 patients (15 %), with one death due to gastric cancer. In four patients who denied screening endoscopy, invasive tumors of the colon (three patients) and stomach developed. Of 33 desmoid tumors, 10 (30 %) were located in the mesentery, 17 (52 %) in the abdominal wall, and 6 (18 %) in extra-abdominal sites. Excision of 12 desmoids was performed in eight patients. Four desmoids were treated by BT and RT and showed full or partial remission. CONCLUSIONS: Provided adequate screening, good long-term control of colorectal tumors is achievable. However, desmoid tumors determine survival and quality of life in many patients. Our data suggest good local control using a combination of brachytherapy/radiotherapy in large desmoids unsuitable for surgical resection