Phase response curve and RNA-sequencing demonstrate spiders’ sensitivity to light and pinpoint candidate light-responsive genes

Posted by
  Phase response curve and RNA-sequencing demonstrate spiders’ sensitivity to light and pinpoint candidate light-responsive genes Abstract Spiders can maintain a wide range of free-running periods while still being entrained to a 24-hour day. To investigate the underlying mechanism of this entrainment, we constructed the phase-response curve (PRC) for the orb weaver, Metazygia wittfeldae , by subjecting the spiders to one-hour light pulses at various times throughout the circadian day. The resulting type 0 PRC showed high amplitude (> 6 hour) phase advance and delays when the light pulse was applied during circadian time (CT) 16–18, including a break point of delays to advances. We then investigated the genetic mechanism of response to light by splitting M. wittfeldae adult females entrained to 12 hours light:12 hours dark (LD 12:12) into two groups. One group received a 1-hour light pulse 5 hours after lights off (equivalent to CT17), and the other group did not. We then sacri...

Oscillating in darkness: Circadian rhythms of cave-dwelling scorpions

Posted by

 

Oscillating in darkness: Circadian rhythms of cave-dwelling scorpions

ABSTRACT

Circadian rhythms, typically synchronized with light–dark cycles, regulate key biological processes in surface organisms. In caves, however, the absence of light may disrupt these rhythms or promote alternative temporal patterns. We examined locomotor activity in two cave-dwelling scorpions with contrasting degrees of subterranean adaptation: Troglorhopalurus translucidus (troglobitic) and Troglorhopalurus lacrau (troglophilic). Activity was monitored under constant darkness (DD), light–dark (LD), and constant light (LL). Both species retained circadian rhythmicity, but with distinct responses: T. translucidus and T. lacrau exhibited diurnal activity under LD and changes in period under DD and LL. These findings demonstrate that circadian regulation persists in cave-adapted scorpions, but its expression is shaped by evolutionary pressures, highlighting the plasticity of biological clocks in light-deprived environments.

de Souza, P. E., & Ferreira, R. L. (2025). Oscillating in darkness: Circadian rhythms of cave-dwelling scorpions. Chronobiology International, 1–8. https://doi.org/10.1080/07420528.2025.2596773