The different effects of structurally related sulfakinins on Drosophila melanogaster odor preference and locomotion suggest involvement of distinct mechanisms

Abstract

Sulfakinins are myoactive peptides and antifeedant factors. Naturally occurring drosulfakinin I (DSK I; FDDYGHMRFNH(2)) and drosulfakinin II (DSK II; GGDDQFDDYGHMRFNH(2)) contain sulfated or nonsulfated tyrosine. We discovered sDSK II and nsDSK II influenced Drosophila melanogaster larval odor preference. However, sDSK I, nsDSK I, MRFNH(2), and saline did not influence odor preference. We discovered sDSK I and nsDSK I influenced larval locomotion. However, sDSK II, nsDSK II, MRFNH(2), and saline did not influence locomotion. Our novel data suggest distinct mechanisms underlie the effects of DSK I and DSK II peptides on odor preference and locomotion, parameters important to many facets of animal survival.

Fig 1A

The effect of saline on odor preference; BuOH odorant. The number of animals (y-axis) and the zone in which they spent a plurality of time (x axis). The left zone reservoir contained butanol (BuOH), the central or neutral zone contained no reservoir (unlabeled), and the right zone reservoir contained water (H2O). The number of animals analyzed was n = 60.

Fig 1B

The effect of saline on odor preference; Ac odorant. The number of animals (y-axis) and the zone in which they spent a plurality of time (x-axis). The left zone reservoir contained acetate (Ac), the central or neutral zone contained no reservoir (unlabeled), and the right zone reservoir contained water (H2O). The number of animals analyzed was n = 60.

Fig 1C

The effect of saline on odor preference; Ac and BuOH odorants. The number of animals (y-axis) and the zone in which they spent a plurality of time (x-axis). The left zone reservoir contained acetate (Ac), the central or neutral zone contained no reservoir (unlabeled), and the right zone reservoir contained butanol (BuOH). The number of animals analyzed was n = 60.

Fig 2A

The effects of saline and MRFNH₂ on odor preference; BuOH odorant. PREF (y axis) equals (# animals in left zone - # animals in right zone)/(total # of animals). The left zone reservoir contained butanol (BuOH) and the right zone reservoir contained water (H2O); x axis. The number of animals analyzed was n = 120 (saline) and n = 113 (MRFNH₂).

Fig 2B

The effects of saline and MRFNH₂ on odor preference; Ac odorant. PREF (y axis) equals (# animals in left zone - # animals in right zone)/(total # of animals). The left zone reservoir contained acetate (Ac) and the right zone reservoir contained water (H2O); x axis. The number of animals analyzed was n = 120 (saline) and n = 112 (MRFNH₂).

Fig 2C

The effects of saline and MRFNH₂ on odor preference; Ac and BuOH odorants. PREF (y axis) equals (# animals in left zone - # animals in right zone)/(total # of animals). The left zone reservoir contained acetate (Ac) and the right zone reservoir contained butanol (BuOH); x axis. The number of animals analyzed were n = 123 (saline) and n = 111 (MRFNH₂).

Fig 3A

The effects of saline and sulfakinins on odor preference; BuOH odorant. A positive PREF index (y axis) indicates animals preferred the odor in the left reservoir butanol (BuOH) compared to the right reservoir water (H2O) in response to the injectant; x axis. Data represent ≥110 larvae assayed for each injectant. Error bars represent % error. An asterisk (*) denotes sulfakinin odor preference data statistically significant compared to saline (p ≤ 0.02).

Fig 3B

The effects of saline and sulfakinins on odor preference; Ac odorant. A positive PREF index (y axis) indicates animals preferred the odor in the left reservoir acetate (Ac) compared to the right reservoir water (H2O), in response to the injectant; x axis. Data represent ≥100 larvae assayed for each injectant. Error bars represent % error. No sulfakinin odor preference data were statistically significant compared to saline (p ≤ 0.02).

Fig 3C

The effects of saline and sulfakinins on odor preference; Ac and BuOH odorants. A positive PREF indicates a systematic preference for the left odorant (Ac); negative PREF indicates a systematic preference for the right odorant (BuOH). Data represent ≥110 larvae assayed for each injectant. Error bars represent % error. An asterisk (*) denotes significant compared to saline (p ≤ 0.02).

Fig 4

The effects of saline and sulfakinins on locomotion. Results displayed as number of lines crossed in 5 minutes. Data represent ≥29 larvae assayed for each injectant. Asterisks represent effects statistically different from saline with p values < 0.001. Error bars represent standard error.