Seasonal plasticity of auditory saccular sensitivity in “sneaker” type II male plainfin midshipman fish, Porichthys notatus

Adult female and nesting (type I) male midshipman fish (Porichthys notatus) exhibit an adaptive form of auditory plasticity for the enhanced detection of social acoustic signals. Whether this adaptive plasticity also occurs in “sneaker” type II males is unknown. Here, we characterize auditory-evoked potentials recorded from hair cells in the saccule of reproductive and non-reproductive “sneaker” type II male midshipman to determine whether this sexual phenotype exhibits seasonal, reproductive state-dependent changes in auditory sensitivity and frequency response to behaviorally relevant auditory stimuli. Saccular potentials were recorded from the middle and caudal region of the saccule while sound was presented via an underwater speaker. Our results indicate saccular hair cells from reproductive type II males had thresholds based on measures of sound pressure and acceleration (re. 1 μPa and 1 ms−2, respectively) that were ~8–21 dB lower than non-reproductive type II males across a broad range of frequencies, which include the dominant higher frequencies in type I male vocalizations. This increase in type II auditory sensitivity may potentially facilitate eavesdropping by sneaker males and their assessment of vocal type I males for the selection of cuckoldry sites during the breeding season

Low-frequency propagation and noise in the intertidal zone

Measurements of ambient noise and short-range propagation (<2m) were made in the intertidal zone with water depths ranging from 50 to 80 cm using vector sensors. The sites selected for the measurements were known nesting areas for plainfin midshipman (Porichthys notatus). Males of this species produce continuous acoustic advertisement calls with fundamental frequencies in the 70 to 100 Hz range. The temporal and spectral structure of these calls must convey information regarding the source’s range, direction, and/or fitness over the maximum detectable range in a complex environment. Both fundamental and harmonic components appear to be above a rapid low-frequency increase in the noise floor due to local wave motion and below the frequency range of several observed noise transients at times with modest wind speeds (<5 mph) and small wave heights (<20cm). There is little evidence of significant propagation differences between specific frequencies within the band of interest

Hearing sensitivity differs between zebrafish lines used in auditory research

Zebrafish are increasingly used in auditory studies, in part due to the development of several transgenic lines that express hair cell-specific fluorescent proteins. However, it is largely unknown how transgene expression influences auditory phenotype. We previously observed reduced auditory sensitivity in adult Brn3c:mGFP transgenic zebrafish, which express membrane-bound green fluorescent protein (GFP) in sensory hair cells. Here, we examine the auditory sensitivity of zebrafish from multiple transgenic and background strains. We recorded auditory evoked potentials in adult animals and observed significantly higher auditory thresholds in three lines that express hair cell-specific GFP. There was no obvious correlation between hair cell density and auditory thresholds, suggesting that reduced sensitivity was not due to a reduction in hair cell density. FM1-43 uptake was reduced in Brn3c:mGFP fish but not in other lines, suggesting that a mechanotransduction defect may be responsible for the auditory phenotype in Brn3c animals, but that alternate mechanisms underlie the increased AEP thresholds in other lines. We found reduced prepulse inhibition (a measure of auditory-evoked behavior) in larval Brn3c animals, suggesting that auditory defects develop early in this line. We also found significant differences in auditory sensitivity between adults of different background strains, akin to strain differences observed in mouse models of auditory function. Our results suggest that researchers should exercise caution when selecting an appropriate zebrafish transgenic or background strain for auditory studies. •Adult zebrafish strains have differing auditory sensitivity.•Sensitivity differences also correlate with fluorescent protein expression.•Larval Brn3c:mGFP fish have reduced auditory-evoked behavior and a potential defect in hair cell transduction.•Hair cell density does not differ between strains.•Caution is warranted when selecting a zebrafish line for auditory research

y483-y487

This archive contains: y483-Cre Et(REx2-SCP1:BGi-Cre-2a-Cer)y483, N = 3 larval zebrafish; y484-Cre, N = 4; y485-Cre, N = 3; y486-Cre, N = 4; y487-Cre, N = 3. Image stacks are compressed nifti files (16 bit), labeled as: "line identifier" - "fish #" - "color channel #". Color channel 01 is the merged RFP and GFP signals of βactin:Switch (Tg(actb2:loxP-eGFP-loxP-ly-TagRFPT)y272) and channel 02 is the Cre expression pattern (RFP signal)

y494-y521

This archive contains: y494-Cre Et(REx2-SCP1:BGi-Cre-2a-Cer)y494, N = 3 larval zebrafish; y495-Cre, N = 3; y519-Cre, N = 4; y520-Cre, N = 3; y521-Cre, N = 3. Image stacks are compressed nifti files (16 bit), labeled as: "line identifier" - "fish #" - "color channel #". Color channel 01 is the merged RFP and GFP signals of βactin:Switch (Tg(actb2:loxP-eGFP-loxP-ly-TagRFPT)y272) and channel 02 is the Cre expression pattern (RFP signal)

y488-y493

This archive contains: y488-Cre Et(REx2-SCP1:BGi-Cre-2a-Cer)y488, N = 3 larval zebrafish; y489-Cre, N = 4; y490-Cre, N = 3; y492-Cre, N = 3; y493-Cre, N = 3. Image stacks are compressed nifti files (16 bit), labeled as: "line identifier" - "fish #" - "color channel #". Color channel 01 is the merged RFP and GFP signals of βactin:Switch (Tg(actb2:loxP-eGFP-loxP-ly-TagRFPT)y272) and channel 02 is the Cre expression pattern (RFP signal)

y542-y546

This archive contains: y542-Cre Et(REx2-SCP1:BGi-Cre-2a-Cer)y542, N = 4 larval zebrafish; y543-Cre, N = 4; y544-Cre, N = 4; y545-Cre, N = 10; y546-Cre, N = 5. Image stacks are compressed nifti files (8 bit), labeled as: "line identifier" - "fish #" - "color channel #". Color channel 01 is the merged RFP and GFP signals of βactin:Switch (Tg(actb2:loxP-eGFP-loxP-ly-TagRFPT)y272) and channel 02 is the Cre expression pattern (RFP signal)

y494-y521

This archive contains: y494-Cre Et(REx2-SCP1:BGi-Cre-2a-Cer)y494, N = 3 larval zebrafish; y495-Cre, N = 3; y519-Cre, N = 4; y520-Cre, N = 3; y521-Cre, N = 3. Image stacks are compressed nifti files (16 bit), labeled as: "line identifier" - "fish #" - "color channel #". Color channel 01 is the merged RFP and GFP signals of βactin:Switch (Tg(actb2:loxP-eGFP-loxP-ly-TagRFPT)y272) and channel 02 is the Cre expression pattern (RFP signal)

y553-y558

This archive contains: y553-Cre Et(REx2-SCP1:BGi-Cre-2a-Cer)y553, N = 6 larval zebrafish; y554-Cre Et(REx2-SCP1:BGi-Cre-2a-Cer)y554, N = 4; y555-Cre Et(REx2-SCP1:BGi-Cre)y555, N = 3; y556-Cre Et(REx2-SCP1:BGi-Cre)y556, N = 4; y557-Cre Et(REx2-SCP1:BGi-Cre)y557, N = 5, y558-Cre Et(REx2-SCP1:BGi-Cre-2a-Cer)y558, N = 4. Image stacks are compressed nifti files (y557 is 16 bit, others are 8 bit), labeled as: "line identifier" - "fish #" - "color channel #". Color channel 01 is the merged RFP and GFP signals of βactin:Switch (Tg(actb2:loxP-eGFP-loxP-ly-TagRFPT)y272) and channel 02 is the Cre expression pattern (RFP signal)

y445-y459

This archive contains: y445-Cre Et(REx2-SCP1:BGi-Cre-2a-Cer)y445, N = 3 larval zebrafish; y456-Cre, N = 3; y457-Cre, N = 3; y458-Cre, N = 4; y459-Cre, N = 3. Image stacks are compressed nifti files (16 bit), labeled as: "line identifier" - "fish #" - "color channel #". Color channel 01 is Tg(elavl3:mCar.zf1)y583 (huC:mCar) and channel 02 is the Cre expression pattern