The Effect of Photoperiod and Light Irradiance on the Antioxidant Circadian System of Two Species of Crayfish from Different Latitudes: Procambarus clarkii and P. digueti¶

Abstract

This work was carried out to study the antioxidant circadian system of two species of crayfish of different latitude origin. We investigated (1) whether both species possess glutathione circadian rhythms and (2) whether both species' rhythms differ in their ability to synchronize to 24 h cycles. Two batches of Procambarus clarkii and P. digueti were kept in (1) light-dark (LD) 12:12 low irradiance (LI) cycles and then exposed to (2) 72 h of complete darkness, (3) LD 12:12 high irradiance (HI), (4) LD 20:4 LI and (5) LD 20:4 HI for 2 weeks. The midgut and hemolymph were sampled and reduced and oxidized glutathione as well as glutathione reductase and glutathione peroxidase were assayed. Cosinor and analysis of variance revealed differences between both species. Procambarus clarkii robust antioxidant circadian rhythms are able to entrain to all conditions resetting to lights on or off. However, the P. digueti weak circadian glutathione system did not entrain to the LD cycles, showing a random distribution of phases. In this species, LD 12:12 and 20:4 HI evidenced significant daily rhythms indicating a damped circadian antioxidative system that is enhanced by the effect of light. This suggests that each species' photoperiodic history determines the adaptive abilities of the circadian antioxidative mechanisms.

Crayfish Procambarus clarkii Retina and Nervous System Exhibit Antioxidant Circadian Rhythms Coupled with Metabolic and Luminous Daily Cycles

“…After 3 days of darkness, the phase relationship increased to w LPO-Glu about 12 h in both. On comparing these values with those obtained in midgut in a previous work (11) (Fig. 6c), GSH-system behavior in the midgut under DD appears to be more similar to OL-B than to retina.…”

“…Our results indicate an apparent strikingly direct effect of light on these rhythms that especially in the retina increase their amplitude greatly under 24 h LD cycles, exhibiting a greater than three-fold GSH increment. This is a larger increase than that found in the brain in this work, and in midgut and hemolymph previously (11). The cyclic luminous condition appears to stimulate the entire GSH system in retina as a response to antagonize the oxidative effect of light on this organ.…”

Daily Light–Dark Cycles Influence Hypoxia‐Inducible Factor 1 and Heat Shock Protein Levels in the Pacemakers of Crayfish

“…Although we did not measure the HIF-1a circadian variations in the current study, the differences between the HIF-1a abundance at 08:00 and 20:00 under all of the experimental conditions (although the differences were not statistically significant because of the high standard errors), and particularly under DD, suggest an HIF-1a circadian rhythm in the central oscillators of crayfish. Interestingly, the relative abundances were similar in the nervous system and retina and reversed under the 20:4 LD condition, which has been reported for other crayfish rhythms under both natural and experimental conditions (2,25). The inverse relationship between the relative abundance of the HIF-1a and HSP70 that was found in the retina, but not in the OL-B complex, under all of the experimental conditions indicates the cross-regulation of both peptides, which has been proposed elsewhere (10).…”

“…In previous studies, we demonstrated that the liver in crayfish possess an antioxidant circadian system, as demonstrated by robust GSH circadian rhythms that persist even when the animal is subjected to extreme latitudinal daily cycles (20 h photoperiod). These rhythms were able to acclimate to 20:4 LD light-day cycles and reset to lights on or off, which suggests strong coupling between the central oscillators (eyestalk and brain) and a possible peripheral oscillator in the liver (2).…”

“…Resistance to environmental stress produced by long, daily photoperiod cycles is expressed in crayfish via decreased ventilation with subsequent hypoxia (1). Light irradiation is a factor that determines reactive oxygen species (ROS) in Procambarus clarkii (2). Because ROS originate with oxygen as a reactant, a decrease in these reactive species should be expected under hypoxic conditions; however, it has been shown that defects in mitochondrial respiration elevate ROS and increase hypoxia-inducible factor 1 (HIF-1) activity (3).…”