title: Inner ear morphological correlates of ultrasonic hearing in frogs.
abstract: Three species of anuran amphibians (Odorrana tormota, Odorrana livida and Huia cavitympanum) have recently been found to detect ultrasounds. We employed immunohistochemistry and confocal microscopy to examine several morphometrics of the inner ear of these ultrasonically sensitive species. We compared morphological data collected from the ultrasound-detecting species with data from Rana pipiens, a frog with a typical anuran upper cut-off frequency of ∼3 kHz. In addition, we examined the ears of two species of Lao torrent frogs, Odorrana chloronota and Amolops daorum, that live in an acoustic environment approximating those of ultrasonically sensitive frogs. Our results suggest that the three ultrasound-detecting species have converged on small-scale functional modifications of the basilar papilla (BP), the high-frequency hearing organ in the frog inner ear. These modifications include: 1. reduced BP chamber volume, 2. reduced tectorial membrane mass, 3. reduced hair bundle length, and 4. reduced hair cell soma length. While none of these factors on its own could account for the US sensitivity of the inner ears of these species, the combination of these factors appears to extend their hearing bandwidth, and facilitate high-frequency/ultrasound detection. These modifications are also seen in the ears of O. chloronota, suggesting that this species is a candidate for high-frequency hearing sensitivity. These data form the foundation for future functional work probing the physiological bases of ultrasound detection by a non-mammalian ear.
authors.affiliation: Abbott Vascular Inc., 3200 Lakeside Drive, Santa Clara, CA 95054 2807, USA.
authors.forename: Victoria S
authors.initials: VS
authors.lastname: Arch
authors.forename: Dwayne D
authors.initials: DD
authors.lastname: Simmons
authors.forename: Patricia M
authors.initials: PM
authors.lastname: Quiñones
authors.forename: Albert S
authors.initials: AS
authors.lastname: Feng
authors.forename: Jianping
authors.initials: J
authors.lastname: Jiang
authors.forename: Bryan L
authors.initials: BL
authors.lastname: Stuart
authors.forename: Jun-Xian
authors.initials: JX
authors.lastname: Shen
authors.forename: Chris
authors.initials: C
authors.lastname: Blair
authors.forename: Peter M
authors.initials: PM
authors.lastname: Narins
mesh_terms: D000199:Actins / Q000032:analysis; D000222:Adaptation, Physiological; D029845:Amphibian Proteins / Q000032:analysis; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D007758:Ear, Inner / Q000033:anatomy & histology* / Q000737:chemistry / Q000502:physiology*; D006309:Hearing; D007150:Immunohistochemistry; D008297:Male; D018613:Microscopy, Confocal; D018995:Myosin Heavy Chains / Q000032:analysis; D009925:Organ of Corti / Q000033:anatomy & histology / Q000502:physiology; D011894:Rana pipiens / Q000033:anatomy & histology* / Q000502:physiology*; D013045:Species Specificity; D014465:Ultrasonics
chemical_list: D000199:Actins; D029845:Amphibian Proteins; D015415:Biomarkers; C089785:myosin VI; D018995:Myosin Heavy Chains