Variation in mitochondrial DNA affects locomotor activity and sleep in Drosophila melanogaster

Abstract

Mitochondria are organelles that produce cellular energy in the form of ATP through oxidative phosphorylation, and this primary function is conserved among many taxa. Locomotion is a trait that is highly reliant on metabolic function and expected to be greatly affected by disruptions to mitochondrial performance. To this end, we aimed to examine how activity and sleep vary between Drosophila melanogaster strains with different geographic origins, how these patterns are affected by mitochondrial DNA (mtDNA) variation, and how breaking up co-evolved mito-nuclear gene combinations affect the studied activity traits. Our results demonstrate that Drosophila strains from different locations differ in sleep and activity, and that females are generally more active than males. By comparing activity and sleep of mtDNA variants introgressed onto a common nuclear background in cytoplasmic hybrid (cybrid) strains, we were able to quantify the among-line variance attributable to mitochondrial DNA, and we establish that mtDNA variation affects both activity and sleep, in a sex-specific manner. Altogether our study highlights the important role that mitochondrial genome variation plays on organismal physiology and behaviour.

WITHDRAWN: Mitochondrial genome variation affects humoral and cell-mediated innate immune responses and infection outcomes

“…Indeed, an antimycin A -treatment as well as OXPHOS cI and cV knockdown in the fat body led to a delayed development time and weakend immune response while mitovariant mtKSA2 and OXPHOS gene knockdowns in hemocytes that had no effect on the development time resulted in an enhanced innate immune response. However, when the locomotion activities and sleep patterns were studied in eight Drosophila cybrid lines, including those studied here, it was shown that especially the males that had the mitovariant mtKSA2 were moving less and sleeping more than the other cybrids [53]. This indicates that the activated immune system of the mtKSA2 flies might be energetically costly and reflect on the activity levels of the mtKSA2 cybrids.…”

Individual identity and environmental conditions explain different aspects of sleep behaviour in wild boar

“…Thus, shorter sleep may represent a facet of the “fast” living strategy where sleep, as a self-maintenance process, is reduced in favour of behaviours that enhance reproductive investment. Consistent with this suggestion, individual-level differences in TST in fruit flies ( Drosophila melanogaster) are genetically determined and shorter-sleeping flies die younger (Cirelli et al 2005; Anderson et al 2022). Given that sleep loss comes at substantial costs (Rechtschaffen et al 1989; Bonnet & Arand 2003; Kushida 2004; Guyon et al 2014), we thus expect that individuals with shorter and more fragmented TST exhibit reduced immunocompetency and impaired cognitive abilities such as decision making (e.g.…”

Mitochondrial background can explain variable costs of immune deployment

“…The lines used herein were generated using donor mtDNA from previously described cybrid lines in a wildtype Oregon-R nuclear background [17,20]. The donor mtDNA in each of the eight lines was sampled from naturally occurring geographic variants [20].…”

“…Variation in the function of the mitochondria may therefore arise through mutations in nDNA or mtDNA, which can affect signalling between the mitochondrial and nuclear genomes, transcription and translation of mitochondrial proteins, and through the interaction between OXPHOS components of both the nDNA and mtDNA [16]. In the absence of infection or immune deployment, variation in mitochondrial function has been associated with decreased lifespan, changes to locomotor activity and reproductive success, as well as developmental time and weight [17][18][19][20][21]. Thus, we may predict variation in mtDNA to generate, or contribute to, heterogeneity in the immune response [16,22,23].…”