Limits...
Sleep in Populations of Drosophila Melanogaster (1,2,3).

Liu C, Haynes PR, Donelson NC, Aharon S, Griffith LC - eNeuro (2015)

Bottom Line: Social interactions between pairs of flies have been shown to affect locomotor activity patterns, but effects on locomotion and sleep patterns have not been assessed for larger populations.Surprisingly, we find that same-sex populations of flies synchronize their sleep/wake activity, resulting in a population sleep pattern, which is similar but not identical to that of isolated individuals.These data support the idea that it is possible to investigate neural mechanisms underlying the effects of population behaviors on sleep by directly looking at a large number of animals in laboratory conditions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biology, National Center for Behavioral Genomics and Volen Center for Complex Systems, Brandeis University , Waltham, Massachusetts 02454-9110.

ABSTRACT
The fruit fly Drosophila melanogaster is a diurnal insect active during the day with consolidated sleep at night. Social interactions between pairs of flies have been shown to affect locomotor activity patterns, but effects on locomotion and sleep patterns have not been assessed for larger populations. Here, we use a commercially available locomotor activity monitor (LAM25H) system to record and analyze sleep behavior. Surprisingly, we find that same-sex populations of flies synchronize their sleep/wake activity, resulting in a population sleep pattern, which is similar but not identical to that of isolated individuals. Like individual flies, groups of flies show circadian and homeostatic regulation of sleep, as well as sexual dimorphism in sleep pattern and sensitivity to starvation and a known sleep-disrupting mutation (amnesiac). Populations of flies, however, exhibit distinct sleep characteristics from individuals. Differences in sleep appear to be due to olfaction-dependent social interactions and change with population size and sex ratio. These data support the idea that it is possible to investigate neural mechanisms underlying the effects of population behaviors on sleep by directly looking at a large number of animals in laboratory conditions.

No MeSH data available.


Related in: MedlinePlus

Diagrams of DAM2 and LAM25H systems. A, DAM2 apparatus. Left, Side view of DAM2 sleep tube (5 × 65 mm) for individual fly recording showing location of infrared beams and food. Right, Cross-section of the tube with the orientation of the two infrared beams. B, LAM25H apparatus. Left, Side view of LAM25H vial (25 × 95 mm) for population recording showing location of infrared beams and food. Right, Cross-section of the vial with the orientation of the nine infrared beams. Dark blue bars and light blue bars indicate transmitters and receivers. Red arrow lines indicate how pairs of infrared beam sensors work, as well as the coverage of the cross-sectional area.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4596024&req=5

Figure 1: Diagrams of DAM2 and LAM25H systems. A, DAM2 apparatus. Left, Side view of DAM2 sleep tube (5 × 65 mm) for individual fly recording showing location of infrared beams and food. Right, Cross-section of the tube with the orientation of the two infrared beams. B, LAM25H apparatus. Left, Side view of LAM25H vial (25 × 95 mm) for population recording showing location of infrared beams and food. Right, Cross-section of the vial with the orientation of the nine infrared beams. Dark blue bars and light blue bars indicate transmitters and receivers. Red arrow lines indicate how pairs of infrared beam sensors work, as well as the coverage of the cross-sectional area.

Mentions: The behavioral patterns of individuals and groups of flies were monitored using the DAM2 and LAM25H systems (Trikinetics), respectively. Diagrams of the apparati are shown in Figure 1. Sleep parameters were analyzed using an in-house MATLAB program described preciously (Donelson et al., 2012) from averages of 2 d of LD data in most experiments. All sleep manipulations (sleep deprivation and starvation) were performed for 1 d. Total sleep, number of sleep episodes, mean episode length, activity while awake, and sleep latency were analyzed for 24 h and/or 12 h light and dark periods (LP and DP). Sleep data were analyzed using Prism 6 software (GraphPad). For experiments that had multiple variables, a two-way ANOVA was performed (Table 1). Multiple comparisons after two-way ANOVA were used for each analysis period (24 h, LP and DP), and were performed to determine which pairs were significantly different and if major effects are significantly different. Holm–Sidak’s/Dunn’s test were used according to the distribution of datasets (Table 2). Datasets are marked with letters (A, B, C, or D) for statistical equivalence groups; i.e., data that are significantly different are indicated by different letters. To evaluate the sleep changes (ΔSleep) during and/or after manipulations, we subtracted the sleep during manipulation days and the sleep after manipulations from its baseline day sleep. The sleep change of the experimental group was compared with the control groups using an unpaired t test if it passed a normality test or Mann–Whitney test if it did not pass a normality test (Table 3). For experiments with different ratio of males in the population, datasets that did not have a normal distribution, nonparametric statistics (Kruskal–Wallis test followed by Dunn’s multiple-pairwise-comparison test) were applied. Otherwise, a one-way ANOVA followed by Holm–Sidak’s test was applied (Tables 4, 5). Figures are all presented as mean ± SEM in a uniform figure style for clarity. For single comparisons, asterisk (*) indicates a significant difference between the experimental group and the control group. The significance level of statistical tests was set to 0.05.


Sleep in Populations of Drosophila Melanogaster (1,2,3).

Liu C, Haynes PR, Donelson NC, Aharon S, Griffith LC - eNeuro (2015)

Diagrams of DAM2 and LAM25H systems. A, DAM2 apparatus. Left, Side view of DAM2 sleep tube (5 × 65 mm) for individual fly recording showing location of infrared beams and food. Right, Cross-section of the tube with the orientation of the two infrared beams. B, LAM25H apparatus. Left, Side view of LAM25H vial (25 × 95 mm) for population recording showing location of infrared beams and food. Right, Cross-section of the vial with the orientation of the nine infrared beams. Dark blue bars and light blue bars indicate transmitters and receivers. Red arrow lines indicate how pairs of infrared beam sensors work, as well as the coverage of the cross-sectional area.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4596024&req=5

Figure 1: Diagrams of DAM2 and LAM25H systems. A, DAM2 apparatus. Left, Side view of DAM2 sleep tube (5 × 65 mm) for individual fly recording showing location of infrared beams and food. Right, Cross-section of the tube with the orientation of the two infrared beams. B, LAM25H apparatus. Left, Side view of LAM25H vial (25 × 95 mm) for population recording showing location of infrared beams and food. Right, Cross-section of the vial with the orientation of the nine infrared beams. Dark blue bars and light blue bars indicate transmitters and receivers. Red arrow lines indicate how pairs of infrared beam sensors work, as well as the coverage of the cross-sectional area.
Mentions: The behavioral patterns of individuals and groups of flies were monitored using the DAM2 and LAM25H systems (Trikinetics), respectively. Diagrams of the apparati are shown in Figure 1. Sleep parameters were analyzed using an in-house MATLAB program described preciously (Donelson et al., 2012) from averages of 2 d of LD data in most experiments. All sleep manipulations (sleep deprivation and starvation) were performed for 1 d. Total sleep, number of sleep episodes, mean episode length, activity while awake, and sleep latency were analyzed for 24 h and/or 12 h light and dark periods (LP and DP). Sleep data were analyzed using Prism 6 software (GraphPad). For experiments that had multiple variables, a two-way ANOVA was performed (Table 1). Multiple comparisons after two-way ANOVA were used for each analysis period (24 h, LP and DP), and were performed to determine which pairs were significantly different and if major effects are significantly different. Holm–Sidak’s/Dunn’s test were used according to the distribution of datasets (Table 2). Datasets are marked with letters (A, B, C, or D) for statistical equivalence groups; i.e., data that are significantly different are indicated by different letters. To evaluate the sleep changes (ΔSleep) during and/or after manipulations, we subtracted the sleep during manipulation days and the sleep after manipulations from its baseline day sleep. The sleep change of the experimental group was compared with the control groups using an unpaired t test if it passed a normality test or Mann–Whitney test if it did not pass a normality test (Table 3). For experiments with different ratio of males in the population, datasets that did not have a normal distribution, nonparametric statistics (Kruskal–Wallis test followed by Dunn’s multiple-pairwise-comparison test) were applied. Otherwise, a one-way ANOVA followed by Holm–Sidak’s test was applied (Tables 4, 5). Figures are all presented as mean ± SEM in a uniform figure style for clarity. For single comparisons, asterisk (*) indicates a significant difference between the experimental group and the control group. The significance level of statistical tests was set to 0.05.

Bottom Line: Social interactions between pairs of flies have been shown to affect locomotor activity patterns, but effects on locomotion and sleep patterns have not been assessed for larger populations.Surprisingly, we find that same-sex populations of flies synchronize their sleep/wake activity, resulting in a population sleep pattern, which is similar but not identical to that of isolated individuals.These data support the idea that it is possible to investigate neural mechanisms underlying the effects of population behaviors on sleep by directly looking at a large number of animals in laboratory conditions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biology, National Center for Behavioral Genomics and Volen Center for Complex Systems, Brandeis University , Waltham, Massachusetts 02454-9110.

ABSTRACT
The fruit fly Drosophila melanogaster is a diurnal insect active during the day with consolidated sleep at night. Social interactions between pairs of flies have been shown to affect locomotor activity patterns, but effects on locomotion and sleep patterns have not been assessed for larger populations. Here, we use a commercially available locomotor activity monitor (LAM25H) system to record and analyze sleep behavior. Surprisingly, we find that same-sex populations of flies synchronize their sleep/wake activity, resulting in a population sleep pattern, which is similar but not identical to that of isolated individuals. Like individual flies, groups of flies show circadian and homeostatic regulation of sleep, as well as sexual dimorphism in sleep pattern and sensitivity to starvation and a known sleep-disrupting mutation (amnesiac). Populations of flies, however, exhibit distinct sleep characteristics from individuals. Differences in sleep appear to be due to olfaction-dependent social interactions and change with population size and sex ratio. These data support the idea that it is possible to investigate neural mechanisms underlying the effects of population behaviors on sleep by directly looking at a large number of animals in laboratory conditions.

No MeSH data available.


Related in: MedlinePlus