TY - JOUR

T1 - Larks, owls, swifts, and woodcocks among fruit flies

T2 - Differential responses of four heritable chronotypes to long and hot summer days

AU - Zakharenko, Lyudmila P.

AU - Petrovskii, Dmitrii V.

AU - Putilov, Arcady A.

N1 - Publisher Copyright: © 2018 Zakharenko et al.

PY - 2018/3/21

Y1 - 2018/3/21

N2 - Purpose: Drosophila melanogaster and our own species share (Homo sapiens) the history of relatively rapid out-of-Africa dispersal. In Eurasia, they had faced a novel adaptive problem of adjustment of their circadian rhythmicity and night sleep episode to seasonal variation in day length and air temperature. Both species usually respond to heat and a short duration of night by reduction of the amount of night sleep and prolongation of “siesta”. To further explore similarities between the two species in the ways of adjustment of their sleep–wake behavior to extreme environmental factors, this study examined the possibility to distinguish four extreme chronotypes among fruit flies and the possibility of the differential response of such chronotypes to light and heat stressors. Materials and methods: Circadian rhythms of locomotor activity and sleep–wake pattern were tested in constant darkness, and four strains of fruit flies originating from three wild populations of Africa, Europe, and the USA were selected to represent four distinct chronotypes: “larks” (early morning and evening activity peaks), “owls” (late morning and evening peaks), “swifts” (early morning and late evening peaks), and “woodcocks” (late morning and early evening peaks). The circadian rhythms and sleep efficiency of the selected chronotypes were further tested under such extreme conditions as either long day (LD20:4 at 20°C) or a combination of LD20:4 with hot temperature (29°C). Results: Despite the identity of such experimental conditions for four chronotypes, their circadian rhythms and sleep timing showed significantly distinct patterns of response to exposure to heat and/or long days. All two-way repeated measures analysis of variances yielded a significant interaction between chronotype and time of the day (P<0.001). Conclusion: An experimental study of heritable chronotypes in the fruit fly can facilitate a search for genetic underpinnings of individual variation in vulnerability to circadian misalignment, maladaptive sleep–wake behavior, and sleep disorders.

AB - Purpose: Drosophila melanogaster and our own species share (Homo sapiens) the history of relatively rapid out-of-Africa dispersal. In Eurasia, they had faced a novel adaptive problem of adjustment of their circadian rhythmicity and night sleep episode to seasonal variation in day length and air temperature. Both species usually respond to heat and a short duration of night by reduction of the amount of night sleep and prolongation of “siesta”. To further explore similarities between the two species in the ways of adjustment of their sleep–wake behavior to extreme environmental factors, this study examined the possibility to distinguish four extreme chronotypes among fruit flies and the possibility of the differential response of such chronotypes to light and heat stressors. Materials and methods: Circadian rhythms of locomotor activity and sleep–wake pattern were tested in constant darkness, and four strains of fruit flies originating from three wild populations of Africa, Europe, and the USA were selected to represent four distinct chronotypes: “larks” (early morning and evening activity peaks), “owls” (late morning and evening peaks), “swifts” (early morning and late evening peaks), and “woodcocks” (late morning and early evening peaks). The circadian rhythms and sleep efficiency of the selected chronotypes were further tested under such extreme conditions as either long day (LD20:4 at 20°C) or a combination of LD20:4 with hot temperature (29°C). Results: Despite the identity of such experimental conditions for four chronotypes, their circadian rhythms and sleep timing showed significantly distinct patterns of response to exposure to heat and/or long days. All two-way repeated measures analysis of variances yielded a significant interaction between chronotype and time of the day (P<0.001). Conclusion: An experimental study of heritable chronotypes in the fruit fly can facilitate a search for genetic underpinnings of individual variation in vulnerability to circadian misalignment, maladaptive sleep–wake behavior, and sleep disorders.

KW - Circadian rhythm

KW - Locomotor activity

KW - Morning-evening preference

KW - Photoperiod

KW - Sleep-wake pattern

KW - Temperature

KW - EVENING OSCILLATOR MODEL

KW - SLEEP

KW - morning-evening preference

KW - CIRCADIAN-RHYTHMS

KW - sleep-wake pattern

KW - COMPONENTS

KW - DEPRESSIVE SYMPTOMS

KW - MORNINGNESS-EVENINGNESS

KW - DROSOPHILA

KW - TEMPERATURE

KW - circadian rhythm

KW - temperature

KW - locomotor activity

KW - photoperiod

KW - ASSOCIATION

KW - CLOCK

UR - http://www.scopus.com/inward/record.url?scp=85057073030&partnerID=8YFLogxK

U2 - 10.2147/NSS.S168905

DO - 10.2147/NSS.S168905

M3 - Article

C2 - 29950910

AN - SCOPUS:85057073030

VL - 10

SP - 181

EP - 191

JO - Nature and Science of Sleep

JF - Nature and Science of Sleep

SN - 1179-1608

ER -