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Mutations of the Drosophila myosin regulatory light chain affect courtship song and reduce reproductive success.

Chakravorty S, Vu H, Foelber V, Vigoreaux JO - PLoS ONE (2014)

Bottom Line: All three mutant males produce a less vigorous pulse song and exhibit impaired mating behavior compared to Control males.These results open the possibility that DMLC2, and perhaps contractile protein genes in general, are partly under sexual selection.That mutations in DMLC2 manifest differently in song and flight suggest that this protein fulfills different roles in song and flight and that stretch activation plays a smaller role in song production than in flight.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, The University of Vermont, Burlington, Vermont, United States of America.

ABSTRACT
The Drosophila indirect flight muscles (IFM) rely on an enhanced stretch-activation response to generate high power output for flight. The IFM is neurally activated during the male courtship song, but its role, if any, in generating the small amplitude wing vibrations that produce the song is not known. Here, we examined the courtship song properties and mating behavior of three mutant strains of the myosin regulatory light chain (DMLC2) that are known to affect IFM contractile properties and impair flight: (i) Dmlc2(Δ2-46) (Ext), an N-terminal extension truncation; (ii) Dmlc2(S66A,S67A) (Phos), a disruption of two MLC kinase phosphorylation sites; and (iii) Dmlc2(Δ2-46;S66A,S67A) (Dual), expressing both mutations. Our results show that the Dmlc2 gene is pleiotropic and that mutations that have a profound effect on flight mechanics (Phos and Dual) have minimal effects on courtship song. None of the mutations affect interpulse interval (IPI), a determinant of species-specific song, and intrapulse frequency (IPF) compared to Control (Dmlc2 (+) rescued strain). However, abnormalities in the sine song (increased frequency) and the pulse song (increased cycles per pulse and pulse length) evident in Ext males are not apparent in Dual males suggesting that Ext and Phos interact differently in song and flight mechanics, given their known additive effect on the latter. All three mutant males produce a less vigorous pulse song and exhibit impaired mating behavior compared to Control males. As a result, females are less receptive to Ext, Phos, and Dual males when a Control male is present. These results open the possibility that DMLC2, and perhaps contractile protein genes in general, are partly under sexual selection. That mutations in DMLC2 manifest differently in song and flight suggest that this protein fulfills different roles in song and flight and that stretch activation plays a smaller role in song production than in flight.

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Effect of Dmlc2 mutations on pulse song properties.(A) Representative pulse song oscillograms from Control, Ext, Phos and Dual males (top to bottom panels, respectively). (B) Phos and Dual males sing with similar cycles per pulse (CPP) and (C) pulse length (PL) compared to Control males. Ext males produce songs with higher CPP and longer PL. (D) All the mutant males produce pulse song with normal intrapulse frequency (IPF), with only the Phos mutants’ IPF showing a slight reduction compared to Ext and Dual. (E) None of the mutations affect interpulse interval. (F) The Dual mutant has significantly reduced pulse duty cycle compared to Control, Ext, and Phos. (G) Amplitude ratio (AMP-RT) of consecutive sine to pulse song is significantly higher in individual (Ext, Phos) and Dual mutants compared to Control. n = 7–8 males for each line. *(p<0.05), ***(p<0.001), ****(p<0.0001) indicate significant differences from Control. § (p<0.05), Ω (p<0.05) and Δ (p<0.05) indicate significant difference from Ext, Phos and Dual mutants, respectively. Error bars indicate SEM.
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pone-0090077-g003: Effect of Dmlc2 mutations on pulse song properties.(A) Representative pulse song oscillograms from Control, Ext, Phos and Dual males (top to bottom panels, respectively). (B) Phos and Dual males sing with similar cycles per pulse (CPP) and (C) pulse length (PL) compared to Control males. Ext males produce songs with higher CPP and longer PL. (D) All the mutant males produce pulse song with normal intrapulse frequency (IPF), with only the Phos mutants’ IPF showing a slight reduction compared to Ext and Dual. (E) None of the mutations affect interpulse interval. (F) The Dual mutant has significantly reduced pulse duty cycle compared to Control, Ext, and Phos. (G) Amplitude ratio (AMP-RT) of consecutive sine to pulse song is significantly higher in individual (Ext, Phos) and Dual mutants compared to Control. n = 7–8 males for each line. *(p<0.05), ***(p<0.001), ****(p<0.0001) indicate significant differences from Control. § (p<0.05), Ω (p<0.05) and Δ (p<0.05) indicate significant difference from Ext, Phos and Dual mutants, respectively. Error bars indicate SEM.

Mentions: The Ext mutant males produce more cycles per pulse (CPP, Figure 3B) and a concomitant increase in pulse length (PL, Figure 3C) compared to Control, Phos, and Dual. In contrast to the reduced or abolished flight wing beat frequencies in the Dmlc2 mutant males (Table 1), the IPF (Figure 3D) is similar in all three mutants compared to Control. Phos males shows slightly lower IPF than Ext or Dual males, but not compared to Control males (Figure 3D). None of the Dmlc2 mutations have an effect on inter-pulse interval (IPI, Figure 3E), one of the salient parameters under sexual selection in the melanogaster subgroup [14], [22], [32].


Mutations of the Drosophila myosin regulatory light chain affect courtship song and reduce reproductive success.

Chakravorty S, Vu H, Foelber V, Vigoreaux JO - PLoS ONE (2014)

Effect of Dmlc2 mutations on pulse song properties.(A) Representative pulse song oscillograms from Control, Ext, Phos and Dual males (top to bottom panels, respectively). (B) Phos and Dual males sing with similar cycles per pulse (CPP) and (C) pulse length (PL) compared to Control males. Ext males produce songs with higher CPP and longer PL. (D) All the mutant males produce pulse song with normal intrapulse frequency (IPF), with only the Phos mutants’ IPF showing a slight reduction compared to Ext and Dual. (E) None of the mutations affect interpulse interval. (F) The Dual mutant has significantly reduced pulse duty cycle compared to Control, Ext, and Phos. (G) Amplitude ratio (AMP-RT) of consecutive sine to pulse song is significantly higher in individual (Ext, Phos) and Dual mutants compared to Control. n = 7–8 males for each line. *(p<0.05), ***(p<0.001), ****(p<0.0001) indicate significant differences from Control. § (p<0.05), Ω (p<0.05) and Δ (p<0.05) indicate significant difference from Ext, Phos and Dual mutants, respectively. Error bars indicate SEM.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3935995&req=5

pone-0090077-g003: Effect of Dmlc2 mutations on pulse song properties.(A) Representative pulse song oscillograms from Control, Ext, Phos and Dual males (top to bottom panels, respectively). (B) Phos and Dual males sing with similar cycles per pulse (CPP) and (C) pulse length (PL) compared to Control males. Ext males produce songs with higher CPP and longer PL. (D) All the mutant males produce pulse song with normal intrapulse frequency (IPF), with only the Phos mutants’ IPF showing a slight reduction compared to Ext and Dual. (E) None of the mutations affect interpulse interval. (F) The Dual mutant has significantly reduced pulse duty cycle compared to Control, Ext, and Phos. (G) Amplitude ratio (AMP-RT) of consecutive sine to pulse song is significantly higher in individual (Ext, Phos) and Dual mutants compared to Control. n = 7–8 males for each line. *(p<0.05), ***(p<0.001), ****(p<0.0001) indicate significant differences from Control. § (p<0.05), Ω (p<0.05) and Δ (p<0.05) indicate significant difference from Ext, Phos and Dual mutants, respectively. Error bars indicate SEM.
Mentions: The Ext mutant males produce more cycles per pulse (CPP, Figure 3B) and a concomitant increase in pulse length (PL, Figure 3C) compared to Control, Phos, and Dual. In contrast to the reduced or abolished flight wing beat frequencies in the Dmlc2 mutant males (Table 1), the IPF (Figure 3D) is similar in all three mutants compared to Control. Phos males shows slightly lower IPF than Ext or Dual males, but not compared to Control males (Figure 3D). None of the Dmlc2 mutations have an effect on inter-pulse interval (IPI, Figure 3E), one of the salient parameters under sexual selection in the melanogaster subgroup [14], [22], [32].

Bottom Line: All three mutant males produce a less vigorous pulse song and exhibit impaired mating behavior compared to Control males.These results open the possibility that DMLC2, and perhaps contractile protein genes in general, are partly under sexual selection.That mutations in DMLC2 manifest differently in song and flight suggest that this protein fulfills different roles in song and flight and that stretch activation plays a smaller role in song production than in flight.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, The University of Vermont, Burlington, Vermont, United States of America.

ABSTRACT
The Drosophila indirect flight muscles (IFM) rely on an enhanced stretch-activation response to generate high power output for flight. The IFM is neurally activated during the male courtship song, but its role, if any, in generating the small amplitude wing vibrations that produce the song is not known. Here, we examined the courtship song properties and mating behavior of three mutant strains of the myosin regulatory light chain (DMLC2) that are known to affect IFM contractile properties and impair flight: (i) Dmlc2(Δ2-46) (Ext), an N-terminal extension truncation; (ii) Dmlc2(S66A,S67A) (Phos), a disruption of two MLC kinase phosphorylation sites; and (iii) Dmlc2(Δ2-46;S66A,S67A) (Dual), expressing both mutations. Our results show that the Dmlc2 gene is pleiotropic and that mutations that have a profound effect on flight mechanics (Phos and Dual) have minimal effects on courtship song. None of the mutations affect interpulse interval (IPI), a determinant of species-specific song, and intrapulse frequency (IPF) compared to Control (Dmlc2 (+) rescued strain). However, abnormalities in the sine song (increased frequency) and the pulse song (increased cycles per pulse and pulse length) evident in Ext males are not apparent in Dual males suggesting that Ext and Phos interact differently in song and flight mechanics, given their known additive effect on the latter. All three mutant males produce a less vigorous pulse song and exhibit impaired mating behavior compared to Control males. As a result, females are less receptive to Ext, Phos, and Dual males when a Control male is present. These results open the possibility that DMLC2, and perhaps contractile protein genes in general, are partly under sexual selection. That mutations in DMLC2 manifest differently in song and flight suggest that this protein fulfills different roles in song and flight and that stretch activation plays a smaller role in song production than in flight.

Show MeSH
Related in: MedlinePlus