Molecular analysis of circadian photosensitivity and diapause in the jewel wasp <i>Nasonia vitripennis</i>

Cycling environmental conditions that vary with latitude have led to the evolution of intricate timing mechanisms. Nasonia vitripennis, a small parasitic wasp (Hymenoptera), is known to have strong light-driven seasonal response in the form of diapause (insect type of hibernation) signalled by short days of upcoming winter, as well as circadian rhythms in behaviours such as locomotor activity. Circadian rhythms are governed by a biological “clock”, whose molecular composition differs between species. Whether this clock also regulates seasonal rhythms is debated, as the regulation of the “seasonal timer” is poorly known. Because Nasonia is missing the clock protein CRYPTOCHROME1, a “light-sensor” for the clock synchronisation in Drosophila, CRYPTOCHROME2 was hypothesised as possible light-sensor in Nasonia. Despite being a core clock component, various in vivo and in vitro experiments did not confirm CRYPTOCHROME2 as a light-sensor in Nasonia. The molecular basis of the seasonal response was studied in a set of genetically variable N. vitripennis lines from a single latitudinal location. Lines varied in the proportion of diapausing broods, under short day conditions, indicating variation in the regulation of the seasonal clock, possibly involving other regulatory pathways. This study has provided insight in the molecular regulation of the Nasonia clock and its light synchronisation, information that is important .for understanding how organisms adapt to a cycling environment

Enhancing autophagy by redox regulation extends lifespan in <i>Drosophila</i>

Redox signalling is an important modulator of diverse biological pathways and processes, and operates through specific post-translational modification of redox-sensitive thiols on cysteine residues 1–4. Critically, redox signalling is distinct from irreversible oxidative damage and functions as a reversible ‘redox switch’ to regulate target proteins. H2O2 acts as the major effector of redox signalling, both directly and through intracellular thiol redox relays 5,6. Dysregulation of redox homeostasis has long been implicated in the pathophysiology of many age-related diseases, as well as in the ageing process itself, however the underlying mechanisms remain largely unclear 7,8. To study redox signalling by H2O2in vivo and explore its involvement in metabolic health and longevity, we used the fruit fly Drosophila as a model organism, with its tractable lifespan and strong evolutionary conservation with mammals 9. Here we report that inducing an endogenous redox-shift, by manipulating levels of the H2O2-degrading enzyme catalase, improves health and robustly extends lifespan in flies, independently of oxidative stress resistance and dietary restriction. We find that the catalase redox-shifted flies are acutely sensitive to starvation stress, which relies on autophagy as a vital survival mechanism. Importantly, we show that autophagy is essential for the lifespan extension of the catalase flies. Furthermore, using redox-inactive knock-in mutants of Atg4a, a major effector of autophagy, we show that the lifespan extension in response to catalase requires a key redox-regulatory cysteine residue, Cys102 in Atg4a. These findings demonstrate that redox regulation of autophagy can extend lifespan, confirming the importance of redox signalling in ageing and as a potential pro-longevity target.</jats:p

Molecular analysis of circadian photosensitivity and diapause in the jewel wasp Nasonia vitripennis

Cycling environmental conditions that vary with latitude have led to the evolution of intricate timing mechanisms. Nasonia vitripennis, a small parasitic wasp (Hymenoptera), is known to have strong light-driven seasonal response in the form of diapause (insect type of hibernation) signalled by short days of upcoming winter, as well as circadian rhythms in behaviours such as locomotor activity. Circadian rhythms are governed by a biological “clock”, whose molecular composition differs between species. Whether this clock also regulates seasonal rhythms is debated, as the regulation of the “seasonal timer” is poorly known. Because Nasonia is missing the clock protein CRYPTOCHROME1, a “light-sensor” for the clock synchronisation in Drosophila, CRYPTOCHROME2 was hypothesised as possible light-sensor in Nasonia. Despite being a core clock component, various in vivo and in vitro experiments did not confirm CRYPTOCHROME2 as a light-sensor in Nasonia. The molecular basis of the seasonal response was studied in a set of genetically variable N. vitripennis lines from a single latitudinal location. Lines varied in the proportion of diapausing broods, under short day conditions, indicating variation in the regulation of the seasonal clock, possibly involving other regulatory pathways. This study has provided insight in the molecular regulation of the Nasonia clock and its light synchronisation, information that is important .for understanding how organisms adapt to a cycling environment