Quantification of TECTA and DFNA5 expression in the developing mouse cochlea.

TECTA and DFNA5 are the mouse orthologues of the human deafness-associated genes TECTA and DFNA5. To determine how expression of these genes is regulated during development, relative mRNA abundance was examined in mice by non-radioactive RT-PCR. TECTA mRNA was detected on embryonic day 15 (E15), increased to its highest level on postnatal day 3 (P3) and then dramatically decreased by P15. Low levels persisted (adulthood, P45 to 67) with mean mRNA abundance after P15 less than 25% of P3 levels. DFNA5 mRNA expression was constant throughout these time points. These results imply that TECTA is transcribed at a particularly high level during tectorial membrane morphogenesis. In contrast, DFNA5 is present in both the developing and mature cochlea.