Gene transcription changes in a locust model of noise-induced deafness

Abstract

Locusts have auditory structures called Müller s organs attached to tympanic membranes on either side of the abdomen. We measured the normalized abundances of 500 different mRNA transcripts in 320 Müller s organs obtained from 160 locusts (Schistocerca gregaria) that had been subjected to a loud continuous 3 kHz tone for 24 hours. Abundance ratios were then measured relative to transcripts from 360 control organs. A histogram of the number of observed transcripts versus their abundance ratios (noise exposed/control) was well fitted by a Cauchy distribution with median value near one. Transcripts below 5% and above 95% of the cumulative distribution function of the fitted Cauchy distribution were selected as putatively different from the expected values of an untreated preparation. This yielded 8 transcripts with ratios increased by noise exposure (ratios 1.689-3.038) and 18 transcripts with reduced ratios (0.069-0.457). Most of the transcripts with increased abundance represented genes responsible for cuticular construction, suggesting extensive remodeling of some or all the cuticular components of the auditory structure, whereas the reduced abundance transcripts were mostly involved in lipid and protein storage and metabolism, suggesting a profound reduction in metabolic activity in response to the overstimulation.