scholarly journals Assessing evidence for adaptive evolution in two hearing-related genes important for high-frequency hearing in echolocating mammals

2021 ◽  
Author(s):  
Hui Wang ◽  
Hanbo Zhao ◽  
Yujia Chu ◽  
Jiang Feng ◽  
Keping Sun
Keyword(s):  
Adaptive Evolution ◽  
Hair Cells ◽  
High Frequency ◽  
Phylogenetic Trees ◽  
Outer Hair Cells ◽  
Functional Domain ◽  
Coding Region ◽  
Selective Pressures ◽  
Wide Range ◽  
Different Parts

Abstract High-frequency hearing is particularly important for echolocating bats and toothed whales. Previously, studies of the hearing-related genes Prestin, KCNQ4, and TMC1 documented that adaptive evolution of high-frequency hearing has taken place in echolocating bats and toothed whales. In this study, we present two additional candidate hearing-related genes, Shh and SK2, that may also have contributed to the evolution of echolocation in mammals. Shh is a member of the vertebrate Hedgehog gene family and is required in the specification of the mammalian cochlea. SK2 is expressed in both inner and outer hair cells, and it plays an important role in the auditory system. The coding region sequences of Shh and SK2 were obtained from a wide range of mammals with and without echolocating ability. The topologies of phylogenetic trees constructed using Shh and SK2 were different; however, multiple molecular evolutionary analyses showed that those two genes experienced different selective pressures in echolocating bats and toothed whales compared to non-echolocating mammals. In addition, several nominally significant positively selected sites were detected in the non-functional domain of the SK2 gene, indicating that different selective pressures were acting on different parts of the SK2 gene. This study has expanded our knowledge of the adaptive evolution of high-frequency hearing in echolocating mammals.

Prestin Expression in Cochlea of Bats Using Different Echolocation Systems

2014 ◽  
Vol 620 ◽  
pp. 248-252
Author(s):  
Qi Jiu Li ◽  
Xian De Zhang ◽  
Ting Ting Xu ◽  
Jiang Xia Yin
Keyword(s):  
Hair Cells ◽  
High Frequency ◽  
Low Frequency ◽  
Motor Protein ◽  
Outer Hair Cells ◽  
Intracellular Potential ◽  
First Time ◽  
Unique Ability

Outer hair cells (OHCs) have a unique ability to contract and elongate in response to changes in intracellular potential, and Prestin is the motor protein of the cochlea of the OHCs. It is the first time to invest the Prestin expression in different bat species. To invest Prestin expression in different bat species, which have different frequency, we did the coronal sections’ staining of the cochlea using immunhistochemistry. Experiment was designed to determine if the high-frequency bats’ OHCs have more expression than the low-frequency bats’OHCs. We found that the expression in three species was similar and had no obvious difference. Though the study of bats Prestin evolution suggested that Prestin has accelerating evolution in echolocation bats with high frequency, our we showed that the Prestin expression has nothing to do with the frequency, and the Prestin expression in high-frequency bats and low-frequency bats is similar.

scholarly journals Oncomodulin Is Expressed Exclusively by Outer Hair Cells in the Organ of Corti

1998 ◽  
Vol 46 (1) ◽  
pp. 29-39 ◽  
Author(s):  
Nobuki Sakaguchi ◽  
Michael T. Henzl ◽  
Isolde Thalmann ◽  
Ruediger Thalmann ◽  
Bradley A. Schulte
Keyword(s):  
Hair Cells ◽  
Calcium Binding ◽  
Organ Of Corti ◽  
Ultrastructural Level ◽  
Outer Hair Cells ◽  
Regulatory Function ◽  
Electron Microscopic ◽  
Wide Range ◽  
Intracellular Organelles ◽  
Functional Relevance

Oncomodulin (OM) is a small, acidic calcium-binding protein first discovered in a rat hepatoma and later found in placental cytotrophoblasts, the pre-implantation embryo, and in a wide variety of neoplastic tissues. OM was considered to be exclusively an oncofetal protein until its recent detection in extracts of the adult guinea pig's organ of Corti. Here we report that light and electron microscopic immunostaining of gerbil, rat, and mouse inner ears with a monoclonal antibody against recombinant rat OM localizes the protein exclusively in cochlear outer hair cells (OHCs). At the ultrastructural level, high gold labeling density was seen overlying the nucleus, cytoplasm, and the cuticular plate of gerbil OHCs. Few, if any, gold particles were present over intracellular organelles and the stereocilia. Staining of a wide range of similarly processed gerbil organs failed to detect immunoreactive OM in any other adult tissues. The mammalian genome encodes one α- and one β-isoform of parvalbumin (PV). The widely distributed α PV exhibits a very high affinity for Ca2+ and is believed to serve as a Ca2+ buffer. By contrast, OM, the mammalian β PV, displays a highly attenuated affinity for Ca2+, consistent with a Ca2+-dependent regulatory function. The exclusive association of OM with cochlear OHCs in mature tissues is likely to have functional relevance. Teleological considerations favor its involvement in regulating some aspect of OHC electromotility. Although the fast electromotile response of OHCs does not require Ca2+, its gain and magnitude are modulated by efferent innervation. Therefore, OM may be involved in mediation of intracellular responses to cholinergic stimulation, which are known to be Ca2+ regulated.

Sensory transduction and frequency selectivity in the basal turn of the guinea-pig cochlea

1992 ◽  
Vol 336 (1278) ◽  
pp. 317-324 ◽  
Keyword(s):  
Guinea Pig ◽  
Hair Cells ◽  
High Frequency ◽  
Basilar Membrane ◽  
Receptor Potential ◽  
Outer Hair Cells ◽  
Sensory Transduction ◽  
Voltage Response ◽  
Operating Range ◽  
Dc Component

Receptor potentials recorded from outer hair cells (ohc ) and inner hair cells (ihc) in the basal highfrequency turn were com pared. The dc component of the ihc receptor potential is maximized to ensure that ihcs can signal a voltage response to high-frequency tones. The ohc dc component is minimized so that ohcs transduce in the most sensitive region of their operating range. The phase and magnitude of ohc receptor potentials were recorded as an indicator of the magnitude and phase of the energy which is fed back to the basilar membrane to provide the basis for the sharp tuning and fine sensitivity of the cochlea to tones. IHC receptor potentials were recorded to assess the net effect of the feedback on the mechanics of the cochlea. It was concluded that ohcs generate feedback which enhances the ihc responses only at the best frequency. At frequencies below cf, ihc dc responses are elicited only when the ohc ac responses begin to saturate.

High-frequency motility of outer hair cells and the cochlear amplifier

Science ◽  
1995 ◽  
Vol 267 (5206) ◽  
pp. 2006-2009 ◽  
Author(s):  
P Dallos ◽  
B. Evans
Keyword(s):  
Hair Cells ◽  
High Frequency ◽  
Outer Hair Cells ◽  
Cochlear Amplifier

scholarly journals Activation of BK and SK Channels by Efferent Synapses on Outer Hair Cells in High-Frequency Regions of the Rodent Cochlea

2015 ◽  
Vol 35 (5) ◽  
pp. 1821-1830 ◽  
Author(s):  
K. N. Rohmann ◽  
E. Wersinger ◽  
J. P. Braude ◽  
S. J. Pyott ◽  
P. A. Fuchs
Keyword(s):  
Hair Cells ◽  
High Frequency ◽  
Outer Hair Cells ◽  
Sk Channels
Sign in / Sign up

Export Citation Format

Share Document